# Unity Connection networking Canonical: https://warmtransfer.net/knowledge/unity-connection-networking Last verified: 2026-09-25 Cisco Unity Connection networking connects multiple Unity Connection locations to share directory data and exchange voice messages[^14][^30]. Architectures include HTTPS networking, legacy intrasite and intersite networking, and VPIM version 2 connections to third-party messaging systems[^38][^52]. ## HTTPS networking An HTTPS network connects at most 25 Unity Connection locations in a hub-and-spoke topology[^11][^9]. Hub locations maintain several HTTPS links, spoke locations have exactly 1 link, and directory data between spokes passes through the hubs[^9]. No location may have more than 5 direct HTTPS links, and the network may be at most 2 levels deep[^12][^8]. HTTPS networking supports only a single-site network, meaning multiple HTTPS networks cannot be connected to one another[^15]. Only Unity Connection 10.x and later servers can join an HTTPS network[^13]. A server cannot join if its display name or SMTP domain matches that of another server already in the network[^45]. For a Unity Connection cluster, only the publisher server is joined to the network[^1]. When a cluster is networked, the other locations must reach it through a smart host that resolves the cluster's SMTP domain to both the publisher and subscriber IP addresses[^2]. Round-trip latency between hub and spoke nodes in an HTTPS network should not exceed 250 ms[^10]. Directory data is exchanged over HTTP on TCP port 8081 or HTTPS on TCP port 8444, while voice messages are exchanged over SMTP on TCP port 25 directly or through a smart host[^14]. Directory replication uses a Feeder service and a Reader service, where the Reader polls the remote Feeder for changes since the last poll and the Feeder answers from its change-tracking data[^5]. By default, the directory-data and recorded-name synchronisation tasks are enabled and run every 15 minutes[^16]. Initial directory replication between newly linked locations can take from a few minutes to a few hours, depending on directory size[^18]. By default, HTTPS networking does not replicate system distribution lists and their membership; enabling the HTTPS link setting 'Include distribution lists and membership when synchronizing directory data' turns it on[^4]. Objects can belong only to local partitions, though remote partitions can still be added to local search spaces[^32]. System call handler owners must be local users[^32]. Cisco's setup task list for an HTTPS network specifies linking servers, then configuring smart hosts and SMTP access for cluster subscribers, then verifying replication, and subsequently configuring search spaces, security, cross-server features, and testing[^17]. The hostname or IP address of an HTTPS-networked location cannot be changed while linked; the location must be removed from the network, modified, and then relinked[^6]. After a location is removed, the 'Remove Objects Associated With Deleted Network Location' task purges its objects, running by default daily at 10:00 p.m., a schedule Cisco recommends keeping[^39]. ## Directory capacity limits The Release 14 HTTPS Networking Guide lists 160,000 users as the directory limit and notes that 14SU2 and earlier support 100,000 users[^47]. The HTTPS network directory limits include 150,000 contacts, 100,000 system distribution lists, 25,000 users per list, 1.5 million total list members, and 20 levels of list nesting[^7]. In legacy intrasite and intersite networking, the global directory limit is 100,000 users and system contacts combined, with the same distribution list limits as HTTPS networking[^31]. | Metric | Legacy (intrasite/intersite) limit | HTTPS network limit | | --- | --- | --- | | Total locations | 10 per site, 20 across 2 sites[^29][^20] | 25[^11] | | User directory capacity | 100,000 combined users and contacts[^31] | 160,000 users (Release 14; 100,000 in 14SU2 and earlier)[^47] | | System contacts | Combined in 100,000 user limit[^31] | 150,000[^7] | | System distribution lists | 100,000[^31] | 100,000[^7] | | Members per list | 25,000[^31] | 25,000[^7] | | Total list members | 1.5 million[^31] | 1.5 million[^7] | | List nesting depth | 20 levels[^31] | 20 levels[^7] | ## Legacy networking (intrasite and intersite) A legacy Unity Connection site (intrasite networking) supports at most 10 Unity Connection servers or clusters[^29]. Within an intrasite network, every location uses SMTP to exchange both directory synchronisation information and voice messages directly with every other location[^30]. Legacy networking tracks directory changes using Unique Sequence Numbers (USNs), where each change increments the location's USN by 1 and is recorded in its database[^50]. An intersite link connects exactly 2 Unity Connection sites, raising the total supported locations from 10 to 20; no more than 2 sites can be linked[^20]. A site can possess only 1 intersite link, preventing simultaneous links to another Unity Connection site and a Cisco Unity site[^23]. Intersite networking is not supported with Cisco Business Edition[^21]. For an intersite link, 1 location in each site acts as the site gateway, carrying all intersite directory synchronisation and voice messaging traffic[^19]. Intersite gateways exchange directory updates over HTTP on port 80 or HTTPS on port 443, and exchange messages over SMTP on port 25 directly or via a smart host[^25]. By default, the intersite Reader polls the remote Feeder every 15 minutes, using separate tasks for directory data and recorded names[^24]. System contacts, system distribution list membership, and VPIM locations and contacts are not replicated across an intersite link[^22]. Message recall does not work across sites linked by an intersite link[^33]. Additionally, dispatch messages and broadcast messages cannot be sent across networked locations, whether intrasite or intersite[^3]. Legacy (SMTP) networking and HTTPS networking cannot run simultaneously in the same network[^38]. SAML SSO cannot be used to access all nodes of an HTTPS, intrasite, or intersite network[^40]. ## VPIM networking Unity Connection VPIM networking uses VPIM version 2 (RFC 3801) over SMTP and MIME to interoperate with third-party voice messaging systems supporting VPIM version 2[^52]. Cisco recommends choosing 1 location in a site as the bridgehead that holds the configuration for VPIM locations and contacts[^51]. ## Migration to HTTPS networking Migrating from legacy networking to HTTPS networking is supported only via a manual procedure; there is no automated migration tool[^35]. Prior to migration, all locations must be upgraded to Release 15, replication must be healthy and in sync with none stalled, and every location must be backed up[^36]. The migration process requires a downtime window whose length depends on the number of locations and directory size[^34]. The flash-cut sequence backs up distribution lists using the Distribution List Syncher, unjoins every location from the legacy network, takes a DRS backup, joins the locations in the HTTPS topology, enables distribution-list sync, and then restores the lists[^37]. ## Cross-server features Cross-server sign-in requires 'Respond to Cross-Server Handoff Requests' enabled on the receiving location, alongside 'Allow Cross-Server Sign-In to this Remote Location' and a cross-server dial string configured on the originating location[^54]. Handoffs are signalled in-band: the originating location holds the caller, dials the receiving location using the dial string, and both locations exchange DTMF tone sequences before call handoff completes[^53]. Only 1 cross-server dial string can be entered per receiving location; thus, an originating location with several phone system integrations requires a dial string usable by all of them[^56]. Enabling cross-server transfer automatically enables cross-server live reply for users permitted live reply by their class of service[^59]. If identified subscriber messaging is disabled, cross-server live reply functions only for messages sent after users sign in to their mailboxes[^55]. When 2 locations are joined by an HTTPS link, video calls using cross-server features are downgraded to audio[^60]. Cisco recommends configuring identical search scopes on originating and receiving locations to prevent situations where a match on 1 location's scope fails to resolve on the other[^58]. ## Troubleshooting When creating an SSL-enabled HTTPS link, Unity Connection verifies that the entered IP address, FQDN, or hostname matches the remote location's web SSL certificate; if mismatched, administrators must supply the matching value or select 'Ignore Certificate Errors'[^42]. Replication status can be checked on the Edit Unity Connection Location page by comparing the Last USN Sent, Received, and Acknowledged fields[^44]. If these fields stop incrementing, replication may be stalled, and the system re-requests records following a default 5-minute timeout[^44]. If RTMT raises a NetworkLoopDetected alert, Cisco instructs administrators to locate the loop using the Network Analyzer tool, unjoin the affected locations, and rejoin them in the correct hierarchy[^41]. A shortage of voice messaging ports can prevent cross-server transfers; Cisco suggests inspecting port utilization using the Unity Connection Port Usage Analyzer[^57]. ## Applicability Applies to: Cisco Unity Connection. Deployments: on-premises. Sources checked 2026-09-25. Prior to migration from legacy networking to HTTPS networking, all locations must be upgraded to Release 15[^36]. Intersite networking is not supported with Cisco Business Edition[^21]. ## What remains uncertain - Networked Unity Connection to Webex Calling voicemail migration (handling cross-server features and distribution lists) is not covered by the sources below. - The authoritative HTTPS network directory user limit for Release 15 (100000 vs 160000) is not covered by the sources below. - Unity Connection networking changes in any release after 15 (limits or deprecation of legacy networking) is not covered by the sources below. - Release 15 SU release notes for networking fixes and changes is not covered by the sources below. - Bandwidth sizing for HTTPS or intersite directory replication and SMTP message traffic is not covered by the sources below. - Security Guide for Unity Connection 15 sections on SSL for networking links and certificate handling is not covered by the sources below. - Community field patterns for stalled replication and link creation failures is not covered by the sources below. - The meaning of the design guide sentence restricting intrasite networking to Business Edition is not covered by the sources below. ## Sources [^1]: For a Unity Connection cluster, only the publisher server is joined to the network. Source: [HTTPS Networking Guide for Cisco Unity Connection Release 15 - Setting Up an HTTPS Network](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/https_networking/b_15cuchttpsnet/b_14cuchttpsnet_chapter_01.html), Setting Up an HTTPS Network > cluster considerations. Checked 2026-09-25. [^2]: When a cluster is networked, the other locations must reach it through a smart host that resolves the cluster's SMTP domain to both the publisher and the subscriber IP addresses. Source: [Networking Guide for Cisco Unity Connection Release 15 - Setting Up Networking Between Cisco Unity Connection Servers](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/networking/guide/b_15cucnetx/b_15cucnetx_chapter_01.html), Setting Up Networking Between Cisco Unity Connection Servers > smart host configuration. Checked 2026-09-25. [^3]: Dispatch messages and broadcast messages cannot be sent across networked locations, whether within a site or between sites. Source: [Networking Guide for Cisco Unity Connection Release 15 - Setting Up Networking Between Cisco Unity Connection Servers](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/networking/guide/b_15cucnetx/b_15cucnetx_chapter_01.html), Setting Up Networking Between Cisco Unity Connection Servers > notes on broadcast and dispatch messages. Checked 2026-09-25. [^4]: By default, HTTPS networking does not replicate system distribution lists and their membership; the HTTPS link setting 'Include distribution lists and membership when synchronizing directory data' turns it on. Source: [Troubleshooting Guide for Cisco Unity Connection Release 15 - Troubleshooting Networking](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/troubleshooting/guide/b_15cuctsg/b_15cuctsg_chapter_01010.html), Troubleshooting Networking > distribution lists in HTTPS networks. Checked 2026-09-25. [^5]: Intersite and HTTPS directory replication use a Feeder service and a Reader service: the Reader polls the remote Feeder for changes since the last poll, and the Feeder answers from its change-tracking data. Source: [Networking Guide for Cisco Unity Connection Release 15 - Overview of Networking Concepts](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/networking/guide/b_15cucnetx/b_15cucnetx_chapter_00.html), Overview of Networking Concepts > intersite networking (replication). Checked 2026-09-25. [^6]: The hostname or IP address of an HTTPS-networked location cannot be changed while it is linked: remove it from the network, make the change, then relink it. Source: [HTTPS Networking Guide for Cisco Unity Connection Release 15 - Making Changes to HTTPS Networking Configuration](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/https_networking/guide/b_15cuchttpsnet/b_15cuchttpsnet_chapter_011.html), Making Changes to HTTPS Networking Configuration > changing hostname or IP address. Checked 2026-09-25. [^7]: The HTTPS network directory limits include 150,000 contacts, 100,000 system distribution lists, 25,000 users per list, 1.5 million total list members and 20 levels of list nesting. Source: [HTTPS Networking Guide for Cisco Unity Connection Release 15 - Overview of HTTPS Networking](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/https_networking/guide/b_15cuchttpsnet/b_15cuchttpsnet_chapter_00.html), Overview of HTTPS Networking > Directory Size Limits. Checked 2026-09-25. [^8]: An HTTPS network may be at most two levels deep. Source: [HTTPS Networking Guide for Cisco Unity Connection Release 15 - Setting Up an HTTPS Network](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/https_networking/b_15cuchttpsnet/b_14cuchttpsnet_chapter_01.html), Setting Up an HTTPS Network > topology determination (hub/spoke rules). Checked 2026-09-25. [^9]: HTTPS networking uses a hub-and-spoke topology: hub locations have several HTTPS links, spoke locations have exactly one, and directory data between spokes passes through the hubs. Source: [HTTPS Networking Guide for Cisco Unity Connection Release 15 - Overview of HTTPS Networking](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/https_networking/guide/b_15cuchttpsnet/b_15cuchttpsnet_chapter_00.html), Overview of HTTPS Networking > hub and spoke topology. Checked 2026-09-25. [^10]: Round-trip latency between hub and spoke nodes in an HTTPS network should not exceed 250 ms. Source: [Design Guide for Cisco Unity Connection 15 - Networking](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/design/b_15cucdg/b_14cucdg_chapter_010011.html), Networking > Designing a Unity Connection Network using HTTPS. Checked 2026-09-25. [^11]: An HTTPS network of Cisco Unity Connection can connect at most 25 Unity Connection locations. Source: [HTTPS Networking Guide for Cisco Unity Connection Release 15 - Overview of HTTPS Networking](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/https_networking/guide/b_15cuchttpsnet/b_15cuchttpsnet_chapter_00.html), Overview of HTTPS Networking > limits discussion. Checked 2026-09-25. [^12]: In an HTTPS network no location may have more than five direct HTTPS links. Source: [HTTPS Networking Guide for Cisco Unity Connection Release 15 - Setting Up an HTTPS Network](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/https_networking/b_15cuchttpsnet/b_14cuchttpsnet_chapter_01.html), Setting Up an HTTPS Network > topology determination (hub/spoke rules). Checked 2026-09-25. [^13]: Only Unity Connection 10.x and later servers can join an HTTPS network. Source: [HTTPS Networking Guide for Cisco Unity Connection Release 15 - Setting Up an HTTPS Network](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/https_networking/b_15cuchttpsnet/b_14cuchttpsnet_chapter_01.html), Setting Up an HTTPS Network > prerequisites. Checked 2026-09-25. [^14]: HTTPS-networked locations exchange directory data over HTTP on TCP port 8081 or HTTPS on TCP port 8444, and exchange voice messages over SMTP on TCP port 25, either directly or through a smart host. Source: [HTTPS Networking Guide for Cisco Unity Connection Release 15 - Setting Up an HTTPS Network](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/https_networking/b_15cuchttpsnet/b_14cuchttpsnet_chapter_01.html), Setting Up an HTTPS Network > prerequisites. Checked 2026-09-25. [^15]: HTTPS networking supports only a single-site network; multiple HTTPS networks cannot be connected to one another. Source: [Design Guide for Cisco Unity Connection 15 - Networking](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/design/b_15cucdg/b_14cucdg_chapter_010011.html), Networking > Designing a Unity Connection Network using HTTPS. Checked 2026-09-25. [^16]: In HTTPS networking the directory-data and recorded-name synchronisation tasks are enabled by default and run every 15 minutes. Source: [HTTPS Networking Guide for Cisco Unity Connection Release 15 - Setting Up an HTTPS Network](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/https_networking/b_15cuchttpsnet/b_14cuchttpsnet_chapter_01.html), Setting Up an HTTPS Network > directory synchronization tasks. Checked 2026-09-25. [^17]: Cisco's HTTPS network setup task list links the servers, then configures smart hosts and SMTP access for cluster subscribers, then verifies replication, and only after that configures search spaces, security, cross-server features and testing. Source: [HTTPS Networking Guide for Cisco Unity Connection Release 15 - Setting Up an HTTPS Network](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/https_networking/b_15cuchttpsnet/b_14cuchttpsnet_chapter_01.html), Setting Up an HTTPS Network > task list for setting up an HTTPS network. Checked 2026-09-25. [^18]: Initial directory replication between newly linked locations can take from a few minutes to a few hours, depending on directory size. Source: [HTTPS Networking Guide for Cisco Unity Connection Release 15 - Setting Up an HTTPS Network](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/https_networking/b_15cuchttpsnet/b_14cuchttpsnet_chapter_01.html), Setting Up an HTTPS Network > verifying replication. Checked 2026-09-25. [^19]: For an intersite link, one location in each site acts as site gateway, and all directory synchronisation and voice messages between the two sites pass between those gateways. Source: [Networking Guide for Cisco Unity Connection Release 15 - Overview of Networking Concepts](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/networking/guide/b_15cucnetx/b_15cucnetx_chapter_00.html), Overview of Networking Concepts > intersite networking. Checked 2026-09-25. [^20]: An intersite link joins exactly two Unity Connection sites, raising the maximum from ten locations to twenty; no more than two sites can be linked. Source: [Networking Guide for Cisco Unity Connection Release 15 - Setting Up Networking Between Cisco Unity Connection Servers](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/networking/guide/b_15cucnetx/b_15cucnetx_chapter_01.html), Setting Up Networking Between Cisco Unity Connection Servers > site limitations. Checked 2026-09-25. [^21]: Intersite networking is not supported with Cisco Business Edition. Source: [Design Guide for Cisco Unity Connection 15 - Networking](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/design/b_15cucdg/b_14cucdg_chapter_010011.html), Networking > Intersite Networking between Two Unity Connection Sites. Checked 2026-09-25. [^22]: System contacts, system distribution list membership and VPIM locations and contacts are not replicated between sites over an intersite link. Source: [Networking Guide for Cisco Unity Connection Release 15 - Overview of Networking Concepts](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/networking/guide/b_15cucnetx/b_15cucnetx_chapter_00.html), Overview of Networking Concepts > replication between sites. Checked 2026-09-25. [^23]: A site can have only one intersite link, so it cannot link to another Unity Connection site and to a Cisco Unity site at the same time. Source: [Design Guide for Cisco Unity Connection 15 - Networking](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/design/b_15cucdg/b_14cucdg_chapter_010011.html), Networking > Intersite Networking between Two Unity Connection Sites. Checked 2026-09-25. [^24]: By default, the intersite Reader polls the remote Feeder every 15 minutes, with separate tasks for directory data and recorded names. Source: [Networking Guide for Cisco Unity Connection Release 15 - Setting Up Networking Between Cisco Unity Connection Servers](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/networking/guide/b_15cucnetx/b_15cucnetx_chapter_01.html), Setting Up Networking Between Cisco Unity Connection Servers > intersite synchronization. Checked 2026-09-25. [^25]: The two intersite gateways exchange directory updates over HTTP on port 80 or HTTPS on port 443, and exchange messages over SMTP on port 25, either directly or through a smart host. Source: [Networking Guide for Cisco Unity Connection Release 15 - Setting Up Networking Between Cisco Unity Connection Servers](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/networking/guide/b_15cucnetx/b_15cucnetx_chapter_01.html), Setting Up Networking Between Cisco Unity Connection Servers > prerequisites for linking sites. Checked 2026-09-25. [^26]: The Release 15 networking guide and system requirements say every server in both sites must run Unity Connection version 15 before two sites can be linked (disputed). Source: [Networking Guide for Cisco Unity Connection Release 15 - Overview of Networking Concepts](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/networking/guide/b_15cucnetx/b_15cucnetx_chapter_00.html), Overview of Networking Concepts > intersite networking. Checked 2026-09-25. [^27]: The Release 15 design guide says all Unity Connection locations in a site must run release 8.0 or later for intersite networking (disputed). Source: [Design Guide for Cisco Unity Connection 15 - Networking](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/design/b_15cucdg/b_14cucdg_chapter_010011.html), Networking > Intersite Networking between Two Unity Connection Sites. Checked 2026-09-25. [^28]: The Release 15 design guide's intrasite section contains the sentence 'Intrasite networking is supported only with Cisco Business Edition 6000/7000'. Source: [Design Guide for Cisco Unity Connection 15 - Networking](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/design/b_15cucdg/b_14cucdg_chapter_010011.html), Networking > Intrasite Networking. Checked 2026-09-25. [^29]: A legacy Unity Connection site (intrasite networking) can contain at most ten Unity Connection servers or clusters, called locations. Source: [Networking Guide for Cisco Unity Connection Release 15 - Overview of Networking Concepts](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/networking/guide/b_15cucnetx/b_15cucnetx_chapter_00.html), Overview of Networking Concepts > intrasite networking. Checked 2026-09-25. [^30]: Within an intrasite network, every location uses SMTP to exchange both directory synchronisation information and voice messages directly with every other location. Source: [Networking Guide for Cisco Unity Connection Release 15 - Overview of Networking Concepts](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/networking/guide/b_15cucnetx/b_15cucnetx_chapter_00.html), Overview of Networking Concepts > intrasite networking. Checked 2026-09-25. [^31]: In legacy (intrasite/intersite) networking the global directory limit is 100,000 users and system contacts combined, with the same limits on distribution lists as HTTPS networking. Source: [Networking Guide for Cisco Unity Connection Release 15 - Overview of Networking Concepts](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/networking/guide/b_15cucnetx/b_15cucnetx_chapter_00.html), Overview of Networking Concepts > directory size limits. Checked 2026-09-25. [^32]: In a Unity Connection network, objects can belong only to local partitions (remote partitions can still be added to local search spaces), and system call handler owners must be local users. Source: [HTTPS Networking Guide for Cisco Unity Connection Release 15 - Overview of HTTPS Networking](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/https_networking/guide/b_15cuchttpsnet/b_15cuchttpsnet_chapter_00.html), Overview of HTTPS Networking > partitions, search spaces and object ownership. Checked 2026-09-25. [^33]: Message recall does not work between sites linked by an intersite link. Source: [Design Guide for Cisco Unity Connection 15 - Networking](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/design/b_15cucdg/b_14cucdg_chapter_010011.html), Networking > Intersite Networking between Two Unity Connection Sites. Checked 2026-09-25. [^34]: Migrating from legacy to HTTPS networking requires a downtime window, and its length depends on the number of locations and the directory size. Source: [HTTPS Networking Guide for Cisco Unity Connection Release 15 - Migration from Legacy Network to HTTPS Network](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/https_networking/guide/b_15cuchttpsnet/b_15cuchttpsnet_chapter_010.html), Migration from Legacy Network to HTTPS Network > overview. Checked 2026-09-25. [^35]: The only supported way to migrate from legacy networking to HTTPS networking is manual; there is no automated migration tool. Source: [Design Guide for Cisco Unity Connection 15 - Networking](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/design/b_15cucdg/b_14cucdg_chapter_010011.html), Networking > Migrating from Legacy (SMTP) Networking to HTTPS Networking. Checked 2026-09-25. [^36]: Before migrating from legacy networking to HTTPS networking, all locations must be upgraded to Release 15, replication must be healthy and in sync with none stalled, and every location must be backed up. Source: [HTTPS Networking Guide for Cisco Unity Connection Release 15 - Migration from Legacy Network to HTTPS Network](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/https_networking/guide/b_15cuchttpsnet/b_15cuchttpsnet_chapter_010.html), Migration from Legacy Network to HTTPS Network > prerequisites. Checked 2026-09-25. [^37]: The flash-cut migration backs up distribution lists with the Distribution List Syncher, unjoins every location from the legacy network, takes a DRS backup, joins the locations in the HTTPS topology, enables distribution-list sync and then restores the lists. Source: [HTTPS Networking Guide for Cisco Unity Connection Release 15 - Migration from Legacy Network to HTTPS Network](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/https_networking/guide/b_15cuchttpsnet/b_15cuchttpsnet_chapter_010.html), Migration from Legacy Network to HTTPS Network > migration steps. Checked 2026-09-25. [^38]: Legacy (SMTP) networking and HTTPS networking cannot run at the same time in the same network. Source: [Design Guide for Cisco Unity Connection 15 - Networking](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/design/b_15cucdg/b_14cucdg_chapter_010011.html), Networking > Designing a Unity Connection Network using HTTPS. Checked 2026-09-25. [^39]: After a location is removed from an HTTPS network, the 'Remove Objects Associated With Deleted Network Location' task purges its objects; by default it runs daily at 10:00 p.m., and Cisco recommends keeping that schedule. Source: [HTTPS Networking Guide for Cisco Unity Connection Release 15 - Making Changes to HTTPS Networking Configuration](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/https_networking/guide/b_15cuchttpsnet/b_15cuchttpsnet_chapter_011.html), Making Changes to HTTPS Networking Configuration > removing a location. Checked 2026-09-25. [^40]: SAML SSO cannot be used to access all the nodes of an HTTPS, intrasite or intersite network. Source: [System Requirements for Cisco Unity Connection Release 15](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/requirements/b_15cucsysreqs.html), Requirements for HTTPS / Intrasite / Intersite Networking. Checked 2026-09-25. [^41]: If RTMT raises a NetworkLoopDetected alert, Cisco says to find the loop with the Network Analyzer tool and then unjoin and rejoin the affected locations in the correct hierarchy. Source: [Troubleshooting Guide for Cisco Unity Connection Release 15 - Troubleshooting Networking](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/troubleshooting/guide/b_15cuctsg/b_15cuctsg_chapter_01010.html), Troubleshooting Networking > network loop detection. Checked 2026-09-25. [^42]: When an SSL-enabled HTTPS link is created, Unity Connection checks that the IP address, FQDN or hostname entered matches the remote location's web SSL certificate; if not, enter the matching value or tick 'Ignore Certificate Errors'. Source: [Troubleshooting Guide for Cisco Unity Connection Release 15 - Troubleshooting Networking](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/troubleshooting/guide/b_15cuctsg/b_15cuctsg_chapter_01010.html), Troubleshooting Networking > HTTPS link creation errors. Checked 2026-09-25. [^43]: The CLI command 'utils cuc networking synchttps' resynchronises selected data across an HTTPS link or location, by USN (up to 10 per command), by object type, or by recorded voice name. Source: [Troubleshooting Guide for Cisco Unity Connection Release 15 - Troubleshooting Networking](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/troubleshooting/guide/b_15cuctsg/b_15cuctsg_chapter_01010.html), Troubleshooting Networking > selective synchronization. Checked 2026-09-25. [^44]: To check replication, compare the Last USN Sent, Received and Acknowledged fields on the Edit Unity Connection Location page; if they stop incrementing, replication may be stalled, and the system re-requests records after a default five-minute timeout. Source: [Troubleshooting Guide for Cisco Unity Connection Release 15 - Troubleshooting Networking](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/troubleshooting/guide/b_15cuctsg/b_15cuctsg_chapter_01010.html), Troubleshooting Networking > directory replication (USN fields; stalled replication). Checked 2026-09-25. [^45]: A server whose display name or SMTP domain matches that of another server already in the network cannot join the network. Source: [HTTPS Networking Guide for Cisco Unity Connection Release 15 - Setting Up an HTTPS Network](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/https_networking/b_15cuchttpsnet/b_14cuchttpsnet_chapter_01.html), Setting Up an HTTPS Network > verifying display names and SMTP domains. Checked 2026-09-25. [^46]: The Release 15 HTTPS Networking Guide lists the HTTPS network directory limit as 100,000 users (disputed). Source: [HTTPS Networking Guide for Cisco Unity Connection Release 15 - Overview of HTTPS Networking](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/https_networking/guide/b_15cuchttpsnet/b_15cuchttpsnet_chapter_00.html), Overview of HTTPS Networking > Directory Size Limits. Checked 2026-09-25. [^47]: The Release 14 HTTPS Networking Guide lists 160,000 users as the directory limit and notes that 14SU2 and earlier support 100,000 users. Source: [HTTPS Networking Guide for Cisco Unity Connection Release 14 - Overview of HTTPS Networking](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/14/https_networking/guide/b_14cuchttpsnet/b_14cuchttpsnet_chapter_00.html), Overview of HTTPS Networking > Directory Size Limits. Checked 2026-09-25. [^48]: The Release 15 design guide states that from Unity Connection 14SU3 onward the network directory limit for users is 160,000 (disputed). Source: [Design Guide for Cisco Unity Connection 15 - Networking](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/design/b_15cucdg/b_14cucdg_chapter_010011.html), Networking > Designing a Unity Connection Network using HTTPS. Checked 2026-09-25. [^49]: The 100,000-user figure in the Release 15 HTTPS guide is probably text left over from before 14SU3 rather than a lower Release 15 limit (inferred). Source: [HTTPS Networking Guide for Cisco Unity Connection Release 14 - Overview of HTTPS Networking](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/14/https_networking/guide/b_14cuchttpsnet/b_14cuchttpsnet_chapter_00.html), Overview of HTTPS Networking > Directory Size Limits (compared against the Release 15 guide section of the same name). Checked 2026-09-25. [^50]: Legacy networking tracks directory changes with Unique Sequence Numbers (USNs): each change increments the location's USN by one and is recorded in its database. Source: [Networking Guide for Cisco Unity Connection Release 15 - Overview of Networking Concepts](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/networking/guide/b_15cucnetx/b_15cucnetx_chapter_00.html), Overview of Networking Concepts > USNs and replication sets. Checked 2026-09-25. [^51]: Cisco recommends choosing one location in a site as the bridgehead that holds the configuration for VPIM locations and contacts. Source: [Design Guide for Cisco Unity Connection 15 - Networking](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/design/b_15cucdg/b_14cucdg_chapter_010011.html), Networking > VPIM Networking. Checked 2026-09-25. [^52]: Unity Connection VPIM networking uses VPIM version 2 (RFC 3801) over SMTP and MIME, and works with third-party voice messaging systems that support VPIM version 2. Source: [Design Guide for Cisco Unity Connection 15 - Networking](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/design/b_15cucdg/b_14cucdg_chapter_010011.html), Networking > VPIM Networking. Checked 2026-09-25. [^53]: Cross-server handoffs are signalled in-band: the originating location holds the caller, dials the receiving location with the cross-server dial string, and the two locations exchange DTMF tone sequences before the call is handed off. Source: [HTTPS Networking Guide for Cisco Unity Connection Release 15 - Cross-Server Sign-In, Transfers, and Live Reply in HTTPS Networking](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/https_networking/guide/b_15cuchttpsnet/b_15cuchttpsnet_chapter_0100.html), Cross-Server Sign-In > how it works; Cross-Server Transfer > how it works. Checked 2026-09-25. [^54]: Cross-server sign-in needs 'Respond to Cross-Server Handoff Requests' enabled on the receiving location, plus 'Allow Cross-Server Sign-In to this Remote Location' and a cross-server dial string on the originating location. Source: [HTTPS Networking Guide for Cisco Unity Connection Release 15 - Cross-Server Sign-In, Transfers, and Live Reply in HTTPS Networking](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/https_networking/guide/b_15cuchttpsnet/b_15cuchttpsnet_chapter_0100.html), Cross-Server Sign-In > task list. Checked 2026-09-25. [^55]: If identified subscriber messaging is disabled, cross-server live reply works only for messages that users sent after signing in to their mailboxes. Source: [HTTPS Networking Guide for Cisco Unity Connection Release 15 - Cross-Server Sign-In, Transfers, and Live Reply in HTTPS Networking](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/https_networking/guide/b_15cuchttpsnet/b_15cuchttpsnet_chapter_0100.html), Cross-Server Live Reply. Checked 2026-09-25. [^56]: Only one cross-server dial string can be entered per receiving location, so an originating location with several phone system integrations needs a dial string that all of them can use. Source: [HTTPS Networking Guide for Cisco Unity Connection Release 15 - Cross-Server Sign-In, Transfers, and Live Reply in HTTPS Networking](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/https_networking/guide/b_15cuchttpsnet/b_15cuchttpsnet_chapter_0100.html), Cross-Server Sign-In > dial string limitation. Checked 2026-09-25. [^57]: A shortage of available voice messaging ports can stop cross-server transfers; Cisco suggests checking port use with the Unity Connection Port Usage Analyzer. Source: [Troubleshooting Guide for Cisco Unity Connection Release 15 - Troubleshooting Networking](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/troubleshooting/guide/b_15cuctsg/b_15cuctsg_chapter_01010.html), Troubleshooting Networking > cross-server sign-in and transfer problems. Checked 2026-09-25. [^58]: Cisco recommends configuring the same search scope on the originating and receiving locations, because a match found on one location's scope may not be found on the other's. Source: [HTTPS Networking Guide for Cisco Unity Connection Release 15 - Cross-Server Sign-In, Transfers, and Live Reply in HTTPS Networking](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/https_networking/guide/b_15cuchttpsnet/b_15cuchttpsnet_chapter_0100.html), Cross-Server Transfer > search scope considerations. Checked 2026-09-25. [^59]: Enabling cross-server transfer automatically enables cross-server live reply for users whose class of service allows live reply. Source: [HTTPS Networking Guide for Cisco Unity Connection Release 15 - Cross-Server Sign-In, Transfers, and Live Reply in HTTPS Networking](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/https_networking/guide/b_15cuchttpsnet/b_15cuchttpsnet_chapter_0100.html), Cross-Server Live Reply. Checked 2026-09-25. [^60]: When two locations are linked by an HTTPS link, a video call that uses a cross-server feature is downgraded to audio. Source: [HTTPS Networking Guide for Cisco Unity Connection Release 15 - Cross-Server Sign-In, Transfers, and Live Reply in HTTPS Networking](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/https_networking/guide/b_15cuchttpsnet/b_15cuchttpsnet_chapter_0100.html), Cross-Server Sign-In / Transfers / Live Reply > video call notes. Checked 2026-09-25.