# Message waiting indicator troubleshooting Canonical: https://warmtransfer.net/knowledge/mwi-troubleshooting Last verified: 2026-09-25 Message waiting indicator (MWI) signaling notifies telephony endpoints when new messages arrive or when mailbox states change[^21][^22]. Troubleshooting MWI failures requires isolating telephony integration settings, port allocations, and protocol-level notification mechanisms across supported systems[^3][^15][^48]. ## How it works When a message arrives in the Cisco Unity Connection message store, Unity Connection notifies the phone system to turn on that user's MWI[^21]. Unity Connection lists saving or deleting a read message, and deleting a new message without listening to it, as triggers for updating the MWI[^22]. A Unity Connection MWI remains on when more messages wait to be heard or when a user marks a listened-to message as unread[^20]. MWI synchronization itself serves as a documented trigger to turn MWIs on or off[^23]. In SIP signaling environments, RFC 3842 defines the SIP event package message-summary for message waiting indication, carried using the body type application/simple-message-summary[^36]. RFC 3842 is a Proposed Standard published in August 2004, authored by R. Mahy of Cisco Systems[^39]. Within an RFC 3842 message summary, the Messages-Waiting line carries yes or no[^37]. Message counts appear per message class as new/old pairs with optional urgent new/old counts in parentheses, such as Voice-Message: 2/8 (0/2)[^34]. The default subscription duration specified by RFC 3842 for the message-summary event package is 1 hour[^35]. ## Integration and protocol troubleshooting In Cisco Unified Communications Manager (Unified CM) SIP integrations with Unity Connection, the integration uses a single trunk per Unity Connection server and eliminates the need to configure directory numbers for voicemail ports and MWI[^51]. The SIP trunk security profile applied to the Unity Connection trunk must have Accept Unsolicited Notification, Accept Out-of-Dialog REFER, and Accept Replaces Header checked[^48][^47]. In Unified CM, the Accept Unsolicited Notification setting directs Unified CM to accept incoming non-INVITE unsolicited notification messages arriving over the SIP trunk[^52]. For Unified CM SCCP integrations, the voicemail system turns MWIs on or off by placing calls to dedicated MWI on or off numbers[^50]. The MWI On and MWI Off numbers are configured as 2 unique extensions in the same partition with Message Waiting Indicator set to On and Off respectively, and use the calling search space used by user phones[^44]. For SCCP integrations only, the MWI On and Off extensions must be in the same calling search space as the phones and voicemail ports, and the dial plan must not contain overlapping patterns[^42][^40]. Furthermore, the Unity Connection port group's MWI On Extension and MWI Off Extension must match the MWI On and Off numbers configured in Unified CM[^45]. Setting the clusterwide Unified CM service parameter Multiple Tenant MWI Modes (Cisco CallManager service, Feature - General) to True instructs Unified CM to apply configured translation patterns to convert voicemail extensions into directory numbers when turning MWIs on or off[^33]. On Cisco IOS SIP voice gateways, MWI is supported through both SUBSCRIBE/NOTIFY and unsolicited NOTIFY sent without a subscription[^30]. The voicemail server is defined using the mwi-server command, where the optional unsolicited keyword specifies unsolicited NOTIFY instead of subscription[^28]. The IOS SIP NOTIFY-to-QSIG MWI translation feature supports only SIP unsolicited NOTIFY, not subscribe-based NOTIFY[^29]. Cisco's IOS SIP MWI documentation directs administrators to use debug ccsip messages to observe SUBSCRIBE/NOTIFY exchanges and debug vpm all to monitor visual MWI changes on analog voice ports[^27]. ## Cisco Unity Connection diagnostics The initial task in Cisco's "MWIs Do Not Turn On or Off" procedure requires running the Check Telephony Configuration test located under Related Links on Telephony Integrations pages[^3]. This test confirms IPv4 communication with the phone system only and does not test IPv6 connectivity[^4]. Cisco's troubleshooting checklist includes the following verification steps: - Voice messaging ports in the integration must be assigned to send MWI requests via the Send MWI Requests check box, those ports must be enabled, and enough ports must be allocated[^15][^46]. Cisco's SCCP integration guidance advises assigning Send MWI Requests to the least busy ports[^41]. - Port groups in the telephony integration must have MWIs enabled[^12]. - MWIs must not be forced off at the phone system level[^11]. Selecting and saving "Force All MWIs Off for This Phone System" turns off all MWIs for that integration[^8]. - User-level MWI enablement is verified via the Enabled check box at Users > Users > Message Waiting Indicators in Unity Connection Administration[^25]. - The user's MWI must have the correct phone system assigned[^26]. Cisco positions enabling MWI macro traces as the last step in the "MWIs Do Not Turn On or Off" troubleshooting procedure, following configuration validation and checks for recent upgrades, restores, or disruptions; the chapter itself does not name individual trace components[^9]. Delays or failures in MWI operation stem from several documented conditions: - Allocating too few ports to send MWI requests can delay notifications; administrators evaluate this using the Port Activity Report in Cisco Unity Connection Serviceability Reports[^6]. - For SCCP integrations with 2 or more port groups, misconfigured port groups are listed as a cause of MWI delay[^5]. - For certain phone systems integrated through PIMG/TIMG units, Unity Connection must send the MWI-off request on the same port that sent the MWI-on request; using a different port causes the turn-off request to fail and leaves the indicator on[^13]. - Running MWI synchronization generates additional MWI requests that can delay notifications for new messages[^7]. Cisco recommends resynchronizing MWIs following a server restore with the Disaster Recovery System, after an upgrade, or after a WAN outage in topologies utilizing distributed voice messaging through SRST routers[^19]. During synchronization, Unity Connection queries its message store to establish MWI status across all phones and resets the applicable indicators[^16]. Synchronizing MWIs on a phone system can degrade system performance, so Cisco advises initiating it during periods of light phone traffic[^18]. In Unity Connection Administration, clicking Run next to "Synchronize All MWIs on This Phone System" on the Phone System Basics page resynchronizes indicators for that specific phone system without impacting others[^17]. ## Endpoint and client considerations Endpoint and client behavior varies by platform configuration: - For Cisco 6800, 7800, and 8800 series multiplatform (MPP) phones, the Voice Mail Subscribe Interval configures the subscription expiry in seconds with a range of 0 to 86400 and a default value of 86400[^32]. The Message Waiting parameter on MPP phones reflects whether the MWI is lit and toggles based on messages from the SIP proxy[^31]. - On the Cisco Wireless Phone 9821 running on Unified CM, the line-level visual MWI policy choices are Use system policy, Light and prompt, Light only, Prompt and None, and Cisco states that "Prompt" does not take effect on this phone[^2]. The audible stutter dial tone MWI only operates on the Cisco Wireless Phone 9821 when Dialing Mode is configured to Off-hook Dialing on the Phone Configuration page[^1]. - For Calling in Webex App on Unified CM, voicemail and MWI depend on an underlying Cisco Unity Connection integration[^54]. Displaying per-line MWI within the Webex App multi call window requires Unified CM 12.5 SU6 or 14.1 SU1 onwards[^53]. - In Webex Calling environments, routing a user's voicemail to an external mailbox delivers all messages to the configured email address and prevents access via phone, Webex App, or User Hub[^55]. When a Webex Calling voicemail group is provisioned with a virtual line, incoming voicemails illuminate the MWI on devices assigned that virtual line number[^59]. ## Applicability Applies to: Cisco Unity Connection, Cisco Unified Communications Manager, SIP, Cisco IOS voice gateways, Cisco IP Phone 6800, Cisco Wireless Phone 9821 on Unified CM, Cisco Webex App calling on Unified CM, and Cisco Webex Calling. Deployments: on-premises, multi-tenant, any, and third-party-call-control. Sources checked 2026-09-25. Webex App multi call window per-line MWI requires Unified CM 12.5 SU6 or 14.1 SU1 onwards[^53]. ## What remains uncertain Webex Calling MWI delivery mechanism to MPP and third-party SIP devices (SUBSCRIBE vs unsolicited NOTIFY) is not covered by the sources below. Unity Connection MWI macro and micro trace names and levels on Release 15 are not covered by the sources below. MWI behaviour on shared lines and line-level Message Waiting Lamp Policy on Unified CM desk phones is not covered by the sources below. MWI with Unity Connection in Webex Calling Dedicated Instance is not covered by the sources below. The Unified CM trace and RTMT method to see inbound NOTIFY message-summary from Unity Connection is not covered by the sources below. Which Webex Calling storage option carries 'Use new message indicator on phone' is not covered by the sources below. MWI during SRST failover and resync after WAN restoration is not covered by the sources below. Webex Calling voicemail API messageStorage mwiEnabled field and required scopes are not covered by the sources below. ## Sources [^1]: On the Cisco Wireless Phone 9821, the audible MWI (stutter dial tone) only takes effect when Dialing Mode is set to Off-hook Dialing on the Phone Configuration page. Source: [Customize Message Waiting Indicator (MWI) policy](https://help.webex.com/article/8fku4d), Audible MWI policy. Checked 2026-09-25. [^2]: For the Cisco Wireless Phone 9821 on Unified CM, the line-level visual MWI policy offers Use system policy, Light and prompt, Light only, Prompt and None, and Cisco states that 'Prompt' does not take effect on this phone. Source: [Customize Message Waiting Indicator (MWI) policy](https://help.webex.com/article/8fku4d), Visual MWI policy (Device > Phone > Line on Device ). Checked 2026-09-25. [^3]: The first task in Cisco's 'MWIs Do Not Turn On or Off' procedure is to run the Check Telephony Configuration test, reachable from Related Links on Telephony Integrations pages. Source: [Troubleshooting Guide for Cisco Unity Connection Release 14 - Troubleshooting Message Waiting Indicators (MWIs)](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/14/troubleshooting/guide/b_14cuctsg/b_14cuctsg_chapter_01110.html), MWI Problems > MWIs Do Not Turn On or Off, task 1. Checked 2026-09-25. [^4]: The Unity Connection Check Telephony Configuration test does not test IPv6 connectivity; it confirms IPv4 communication with the phone system only. Source: [Troubleshooting Guide for Cisco Unity Connection Release 15 - Troubleshooting Message Waiting Indicators (MWIs)](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/troubleshooting/guide/b_15cuctsg/b_15cuctsg_chapter_01110.html), MWIs Do Not Turn On or Off, Check Telephony Configuration task note. Checked 2026-09-25. [^5]: For SCCP integrations that have two or more port groups, Cisco notes that not all port groups may be configured correctly, which is a listed cause of MWI delay. Source: [Troubleshooting Guide for Cisco Unity Connection Release 14 - Troubleshooting Message Waiting Indicators (MWIs)](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/14/troubleshooting/guide/b_14cuctsg/b_14cuctsg_chapter_01110.html), MWI Problems > Delay for MWIs to Turn On or Off. Checked 2026-09-25. [^6]: Too few ports assigned to send MWI requests can delay MWIs; Cisco directs administrators to the Port Activity Report in Cisco Unity Connection Serviceability Reports to evaluate this. Source: [Troubleshooting Guide for Cisco Unity Connection Release 15 - Troubleshooting Message Waiting Indicators (MWIs)](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/troubleshooting/guide/b_15cuctsg/b_15cuctsg_chapter_01110.html), MWI Problems > Delay for MWIs to Turn On or Off. Checked 2026-09-25. [^7]: Running MWI synchronization for a phone system integration can delay MWIs for new messages because of the additional MWI requests being processed. Source: [Troubleshooting Guide for Cisco Unity Connection Release 15 - Troubleshooting Message Waiting Indicators (MWIs)](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/troubleshooting/guide/b_15cuctsg/b_15cuctsg_chapter_01110.html), MWI Problems > Delay for MWIs to Turn On or Off. Checked 2026-09-25. [^8]: Checking 'Force All MWIs Off for This Phone System' and saving turns off all MWIs for that phone system integration. Source: [Troubleshooting Guide for Cisco Unity Connection Release 14 - Troubleshooting Message Waiting Indicators (MWIs)](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/14/troubleshooting/guide/b_14cuctsg/b_14cuctsg_chapter_01110.html), MWIs Do Not Turn On or Off, task on MWIs forced off at phone system level. Checked 2026-09-25. [^9]: Cisco places enabling MWI macro traces as the last step of the 'MWIs Do Not Turn On or Off' procedure, after the configuration checks and a check for a recent upgrade, restore or disruption; the chapter itself does not name individual trace components. Source: [Troubleshooting Guide for Cisco Unity Connection Release 15 - Troubleshooting Message Waiting Indicators (MWIs)](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/troubleshooting/guide/b_15cuctsg/b_15cuctsg_chapter_01110.html), MWIs Do Not Turn On or Off, final task. Checked 2026-09-25. [^10]: For the symptom 'No Message Count Sent on Phone When MWI is On', message counts are controlled per user under Playback Message Settings (Message Count Totals, Voice, Email, Fax and Receipt Message Counts). Source: [Troubleshooting Guide for Cisco Unity Connection Release 15 - Troubleshooting Message Waiting Indicators (MWIs)](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/troubleshooting/guide/b_15cuctsg/b_15cuctsg_chapter_01110.html), MWI Problems > No Message Count Sent on Phone When MWI is On. Checked 2026-09-25. [^11]: Cisco's MWI checklist requires confirming that MWIs are not forced off at the phone system level. Source: [Troubleshooting Guide for Cisco Unity Connection Release 14 - Troubleshooting Message Waiting Indicators (MWIs)](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/14/troubleshooting/guide/b_14cuctsg/b_14cuctsg_chapter_01110.html), MWI Problems > MWIs Do Not Turn On or Off, task 8. Checked 2026-09-25. [^12]: Cisco's MWI checklist requires confirming that the port groups in the integration have MWIs enabled. Source: [Troubleshooting Guide for Cisco Unity Connection Release 14 - Troubleshooting Message Waiting Indicators (MWIs)](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/14/troubleshooting/guide/b_14cuctsg/b_14cuctsg_chapter_01110.html), MWI Problems > MWIs Do Not Turn On or Off, task 5. Checked 2026-09-25. [^13]: For some phone systems integrated through PIMG/TIMG units, Unity Connection must turn an MWI off on the same port that turned it on; if a different port is used, the MWI-off request fails and the MWI stays on. Source: [Troubleshooting Guide for Cisco Unity Connection Release 14 - Troubleshooting Message Waiting Indicators (MWIs)](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/14/troubleshooting/guide/b_14cuctsg/b_14cuctsg_chapter_01110.html), MWI Problems > MWIs Turn On but Do Not Turn Off. Checked 2026-09-25. [^14]: On phone systems that need port memory, deleting or reconfiguring voice messaging ports can cause MWIs to turn on but not turn off. Source: [Troubleshooting Guide for Cisco Unity Connection Release 14 - Troubleshooting Message Waiting Indicators (MWIs)](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/14/troubleshooting/guide/b_14cuctsg/b_14cuctsg_chapter_01110.html), MWI Problems > MWIs Turn On but Do Not Turn Off. Checked 2026-09-25. [^15]: Cisco's MWI checklist requires confirming that voice messaging ports in the phone system integration are assigned to send MWI requests, that those ports are enabled, and that enough ports are so assigned. Source: [Troubleshooting Guide for Cisco Unity Connection Release 14 - Troubleshooting Message Waiting Indicators (MWIs)](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/14/troubleshooting/guide/b_14cuctsg/b_14cuctsg_chapter_01110.html), MWI Problems > MWIs Do Not Turn On or Off, tasks 2 to 4. Checked 2026-09-25. [^16]: When MWIs are synchronized, Unity Connection queries its message store to determine the MWI status for all phones and resets the applicable MWIs. Source: [Troubleshooting Guide for Cisco Unity Connection Release 15 - Troubleshooting Message Waiting Indicators (MWIs)](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/troubleshooting/guide/b_15cuctsg/b_15cuctsg_chapter_01110.html), MWIs Do Not Turn On or Off, synchronization task. Checked 2026-09-25. [^17]: In Unity Connection Administration, selecting Run next to 'Synchronize All MWIs on This Phone System' on the Phone System Basics page synchronizes MWIs for that phone system without affecting MWIs on other phone systems. Source: [System Administration Guide for Cisco Unity Connection Release 15 - Telephony Integration](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/administration/guide/b_15cucsag/b_15cucsag_chapter_0110.html), Phone System > Phone System Basics. Checked 2026-09-25. [^18]: Cisco warns that synchronizing MWIs for a phone system may affect system performance and recommends doing it when phone traffic is light. Source: [Troubleshooting Guide for Cisco Unity Connection Release 15 - Troubleshooting Message Waiting Indicators (MWIs)](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/troubleshooting/guide/b_15cuctsg/b_15cuctsg_chapter_01110.html), MWIs Do Not Turn On or Off, synchronization procedure note. Checked 2026-09-25. [^19]: Cisco recommends resynchronizing MWIs after a Unity Connection server is restored with the Disaster Recovery System, after upgrading, and after a WAN outage in a system that has distributed voice messaging through SRST routers. Source: [Troubleshooting Guide for Cisco Unity Connection Release 15 - Troubleshooting Message Waiting Indicators (MWIs)](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/troubleshooting/guide/b_15cuctsg/b_15cuctsg_chapter_01110.html), MWIs Do Not Turn On or Off, task on upgraded/restored/disrupted server. Checked 2026-09-25. [^20]: A Unity Connection MWI stays on when more messages are waiting to be heard or when the user marks a listened-to message as unread. Source: [Troubleshooting Guide for Cisco Unity Connection Release 15 - Troubleshooting Message Waiting Indicators (MWIs)](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/troubleshooting/guide/b_15cuctsg/b_15cuctsg_chapter_01110.html), Triggers for Turning MWIs On and Off. Checked 2026-09-25. [^21]: When a message for a user arrives in the Cisco Unity Connection message store, Unity Connection notifies the phone system to turn on that user's MWI. Source: [Troubleshooting Guide for Cisco Unity Connection Release 15 - Troubleshooting Message Waiting Indicators (MWIs)](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/troubleshooting/guide/b_15cuctsg/b_15cuctsg_chapter_01110.html), Triggers for Turning MWIs On and Off. Checked 2026-09-25. [^22]: Unity Connection lists a user saving or deleting a read message, and a user deleting a new message without listening to it, as triggers for updating the MWI. Source: [Troubleshooting Guide for Cisco Unity Connection Release 15 - Troubleshooting Message Waiting Indicators (MWIs)](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/troubleshooting/guide/b_15cuctsg/b_15cuctsg_chapter_01110.html), Triggers for Turning MWIs On and Off. Checked 2026-09-25. [^23]: MWI synchronization is itself one of the documented triggers for Unity Connection to turn MWIs on or off. Source: [Troubleshooting Guide for Cisco Unity Connection Release 15 - Troubleshooting Message Waiting Indicators (MWIs)](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/troubleshooting/guide/b_15cuctsg/b_15cuctsg_chapter_01110.html), Triggers for Turning MWIs On and Off. Checked 2026-09-25. [^24]: The Unity Connection phone system setting 'Use Same Port for Enabling and Disabling MWIs' is checked when the integration uses the same voice messaging port to turn an MWI on and off; Cisco says to uncheck it together with 'Force All MWIs Off for This Phone System' to disable that behaviour without leaving MWIs on for users with no messages. Source: [System Administration Guide for Cisco Unity Connection Release 15 - Telephony Integration](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/administration/guide/b_15cucsag/b_15cucsag_chapter_0110.html), Phone System > Phone System Basics. Checked 2026-09-25. [^25]: Whether MWI is enabled for a user is checked with the Enabled check box at Users > Users > Message Waiting Indicators in Cisco Unity Connection Administration. Source: [Troubleshooting Guide for Cisco Unity Connection Release 14 - Troubleshooting Message Waiting Indicators (MWIs)](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/14/troubleshooting/guide/b_14cuctsg/b_14cuctsg_chapter_01110.html), MWI Problems > MWIs Do Not Turn On or Off, task 9. Checked 2026-09-25. [^26]: Cisco's MWI checklist requires confirming that the correct phone system is assigned to the user's MWI. Source: [Troubleshooting Guide for Cisco Unity Connection Release 14 - Troubleshooting Message Waiting Indicators (MWIs)](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/14/troubleshooting/guide/b_14cuctsg/b_14cuctsg_chapter_01110.html), MWI Problems > MWIs Do Not Turn On or Off, task 10. Checked 2026-09-25. [^27]: Cisco's IOS SIP MWI guide uses debug ccsip messages to observe the SUBSCRIBE/NOTIFY exchange and debug vpm all to observe visual MWI state changes on analog voice ports. Source: [SIP Configuration Guide, Cisco IOS Release 15M&T - Configuring SIP MWI Features](https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/voice/sip/configuration/15-mt/sip-config-15-mt-book/voi-sip-mwi.html), Configuring SIP MWI Features, verification and troubleshooting section. Checked 2026-09-25. [^28]: On Cisco IOS SIP gateways the voicemail server is set with the mwi-server command, and its optional unsolicited keyword selects unsolicited NOTIFY rather than subscription. Source: [SIP Configuration Guide, Cisco IOS Release 15M&T - Configuring SIP MWI Features](https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/voice/sip/configuration/15-mt/sip-config-15-mt-book/voi-sip-mwi.html), Configuring SIP MWI Features, configuration tasks (mwi-server). Checked 2026-09-25. [^29]: The IOS SIP NOTIFY-to-QSIG MWI translation feature supports only SIP unsolicited NOTIFY, not subscribe-based NOTIFY. Source: [SIP Configuration Guide, Cisco IOS Release 15M&T - Configuring SIP MWI Features](https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/voice/sip/configuration/15-mt/sip-config-15-mt-book/voi-sip-mwi.html), Configuring SIP MWI Features, restrictions for SIP MWI NOTIFY QSIG translation. Checked 2026-09-25. [^30]: Cisco IOS SIP voice gateways support MWI both through SUBSCRIBE/NOTIFY and through unsolicited NOTIFY sent by the voicemail server without a subscription. Source: [SIP Configuration Guide, Cisco IOS Release 15M&T - Configuring SIP MWI Features](https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/voice/sip/configuration/15-mt/sip-config-15-mt-book/voi-sip-mwi.html), Configuring SIP MWI Features, information section. Checked 2026-09-25. [^31]: On MPP phones, the Message Waiting parameter indicates whether the phone's MWI is lit and is toggled by a message from the SIP proxy. Source: [Cisco IP Desk Phone with Multiplatform Firmware (MPP) Administration Guide - Voicemail Configuration](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cuipph/MPP/common/ag_desk_mpp_6800_7800_8800/tpcc_b_cisco-ip-desk-phone-multiplatform/tpcc_m_voice-mail-configuration-1131.html), Voicemail Configuration, parameter 'Message Waiting'. Checked 2026-09-25. [^32]: On Cisco 6800/7800/8800 multiplatform (MPP) phones, Voice Mail Subscribe Interval sets the expiry in seconds of the phone's subscription to the voicemail server, with a range of 0 to 86400 and a default of 86400. Source: [Cisco IP Desk Phone with Multiplatform Firmware (MPP) Administration Guide - Voicemail Configuration](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cuipph/MPP/common/ag_desk_mpp_6800_7800_8800/tpcc_b_cisco-ip-desk-phone-multiplatform/tpcc_m_voice-mail-configuration-1131.html), Voicemail Configuration, parameter 'Voice Mail Subscribe Interval'. Checked 2026-09-25. [^33]: Setting the Unified CM clusterwide service parameter Multiple Tenant MWI Modes (Cisco CallManager service, Feature - General) to True makes Unified CM apply configured translation patterns to convert voicemail extensions into directory numbers when turning MWIs on or off. Source: [Cisco Unified Communications Manager SIP Integration Guide for Cisco Unity Connection Release 15 - Setting Up a Cisco Unified Communications Manager SIP Trunk Integration](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/integration/cucm_sip/b_15cucintcucmsip/b_14cucintcucmsip_chapter_010.html), Setting Up a Cisco Unified CM SIP Trunk Integration, voice mail server service parameters steps 4 to 5. Checked 2026-09-25. [^34]: RFC 3842 message counts are expressed per message class as new/old pairs with optional urgent new/old counts in parentheses, e.g. 'Voice-Message: 2/8 (0/2)'. Source: [RFC 3842: A Message Summary and Message Waiting Indication Event Package for the Session Initiation Protocol (SIP)](https://www.rfc-editor.org/rfc/rfc3842.html), Section 4 (examples) and Section 5 (formal syntax). Checked 2026-09-25. [^35]: RFC 3842 sets the default subscription duration for the message-summary event package to one hour. Source: [RFC 3842: A Message Summary and Message Waiting Indication Event Package for the Session Initiation Protocol (SIP)](https://www.rfc-editor.org/rfc/rfc3842.html), Section 3 (subscription duration). Checked 2026-09-25. [^36]: RFC 3842 defines the SIP event package 'message-summary' for message waiting indication, carried in the body type application/simple-message-summary. Source: [RFC 3842: A Message Summary and Message Waiting Indication Event Package for the Session Initiation Protocol (SIP)](https://www.rfc-editor.org/rfc/rfc3842.html), Section 3 (event package definition). Checked 2026-09-25. [^37]: In an RFC 3842 message summary, the Messages-Waiting line carries yes or no to indicate whether messages are waiting. Source: [RFC 3842: A Message Summary and Message Waiting Indication Event Package for the Session Initiation Protocol (SIP)](https://www.rfc-editor.org/rfc/rfc3842.html), Section 3 (NOTIFY bodies) and Section 5 (formal syntax). Checked 2026-09-25. [^38]: RFC 3842 describes message-summary notifications within a SUBSCRIBE-established subscription and does not appear to define an unsolicited (subscription-less) NOTIFY mode; vendor 'unsolicited NOTIFY' MWI is therefore a vendor practice rather than something RFC 3842 specifies (inferred). Source: [RFC 3842: A Message Summary and Message Waiting Indication Event Package for the Session Initiation Protocol (SIP)](https://www.rfc-editor.org/rfc/rfc3842.html), Section 3 (notifier generation of NOTIFY requests); absence across document. Checked 2026-09-25. [^39]: RFC 3842 is a Proposed Standard published in August 2004, authored by R. Mahy of Cisco Systems. Source: [Information on RFC 3842](https://www.rfc-editor.org/info/rfc3842), RFC Editor info page, status and date fields. Checked 2026-09-25. [^40]: For Cisco Unified CM SCCP integrations only, the dial plan must not contain patterns that overlap the MWI extensions. Source: [Troubleshooting Guide for Cisco Unity Connection Release 15 - Troubleshooting Message Waiting Indicators (MWIs)](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/troubleshooting/guide/b_15cuctsg/b_15cuctsg_chapter_01110.html), MWIs Do Not Turn On or Off, SCCP-only dial plan task (task 12 in the Release 14 ordering). Checked 2026-09-25. [^41]: Cisco's SCCP integration guide advises assigning Send MWI Requests to the least busy ports. Source: [Cisco Unified Communications Manager SCCP Integration Guide for Cisco Unity Connection Release 15 - Setting Up a Cisco Unified Communications Manager SCCP Integration](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/integration/cucm_sccp/b_15cucintcucmskinny/b_14cucintcucmskinny_chapter_010.html), Setting Up a Cisco Unified CM SCCP Integration, port settings (Port Basics). Checked 2026-09-25. [^42]: For Cisco Unified CM SCCP integrations only, the MWI On and Off extensions must be in the same calling search space as the phones and voicemail ports. Source: [Troubleshooting Guide for Cisco Unity Connection Release 15 - Troubleshooting Message Waiting Indicators (MWIs)](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/troubleshooting/guide/b_15cuctsg/b_15cuctsg_chapter_01110.html), MWIs Do Not Turn On or Off, SCCP-only calling search space task (task 11 in the Release 14 ordering). Checked 2026-09-25. [^43]: For SCCP integrations, the MWI On and MWI Off directory numbers are created in Cisco Unified CM Administration under Advanced Features > Voice Mail > Message Waiting. Source: [Cisco Unified Communications Manager SCCP Integration Guide for Cisco Unity Connection Release 15 - Setting Up a Cisco Unified Communications Manager SCCP Integration](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/integration/cucm_sccp/b_15cucintcucmskinny/b_14cucintcucmskinny_chapter_010.html), Specifying the MWI Directory Numbers, step 1. Checked 2026-09-25. [^44]: The SCCP integration guide has the MWI On and MWI Off numbers configured as two unique extensions in the same partition (the voice mail pilot partition in its example), with Message Waiting Indicator set to On and Off respectively and the calling search space used by user phones. Source: [Cisco Unified Communications Manager SCCP Integration Guide for Cisco Unity Connection Release 15 - Setting Up a Cisco Unified Communications Manager SCCP Integration](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/integration/cucm_sccp/b_15cucintcucmskinny/b_14cucintcucmskinny_chapter_010.html), Specifying the MWI Directory Numbers, steps 2 to 7. Checked 2026-09-25. [^45]: In an SCCP integration, the Unity Connection port group's MWI On Extension and MWI Off Extension must match the MWI On and Off numbers configured in Unified CM. Source: [Cisco Unified Communications Manager SCCP Integration Guide for Cisco Unity Connection Release 15 - Setting Up a Cisco Unified Communications Manager SCCP Integration](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/integration/cucm_sccp/b_15cucintcucmskinny/b_14cucintcucmskinny_chapter_010.html), Setting Up a Cisco Unified CM SCCP Integration, port group settings. Checked 2026-09-25. [^46]: On a Unity Connection voice messaging port, the Send MWI Requests check box designates that port for turning MWIs on and off. Source: [Cisco Unified Communications Manager SIP Integration Guide for Cisco Unity Connection Release 15 - Setting Up a Cisco Unified Communications Manager SIP Trunk Integration](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/integration/cucm_sip/b_15cucintcucmsip/b_14cucintcucmsip_chapter_010.html), Setting Up a Cisco Unified CM SIP Trunk Integration, port settings table. Checked 2026-09-25. [^47]: The same Unity Connection SIP trunk security profile must also have Accept Out-of-Dialog REFER and Accept Replaces Header checked. Source: [Cisco Unified Communications Manager SIP Integration Guide for Cisco Unity Connection Release 15 - Setting Up a Cisco Unified Communications Manager SIP Trunk Integration](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/integration/cucm_sip/b_15cucintcucmsip/b_14cucintcucmsip_chapter_010.html), Setting Up a Cisco Unified CM SIP Trunk Integration, SIP trunk security profile task step 3, Table 2. Checked 2026-09-25. [^48]: For a Unified CM SIP trunk integration with Unity Connection, the SIP trunk security profile used by the Unity Connection trunk must have Accept Unsolicited Notification checked. Source: [Cisco Unified Communications Manager SIP Integration Guide for Cisco Unity Connection Release 15 - Setting Up a Cisco Unified Communications Manager SIP Trunk Integration](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/integration/cucm_sip/b_15cucintcucmsip/b_14cucintcucmsip_chapter_010.html), Setting Up a Cisco Unified CM SIP Trunk Integration, SIP trunk security profile task step 3, Table 2. Checked 2026-09-25. [^49]: Unity Connection SIP-trunk MWI appears to depend on Unified CM accepting unsolicited SIP NOTIFY on the trunk, so an unchecked Accept Unsolicited Notification box on the Unity Connection trunk's security profile is a likely cause of SIP-integrated MWIs failing to change (inferred). Source: [Cisco Unified Communications Manager SIP Integration Guide for Cisco Unity Connection Release 15 - Setting Up a Cisco Unified Communications Manager SIP Trunk Integration](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/integration/cucm_sip/b_15cucintcucmsip/b_14cucintcucmsip_chapter_010.html), SIP trunk security profile task step 3, Table 2; read with the Accept Unsolicited Notification field description in cisco-cucm15-security-sip-trunk-profile. Checked 2026-09-25. [^50]: In an SCCP integration, the voicemail system sends MWIs by calling a message-waiting on number or off number in Unified CM. Source: [System Configuration Guide for Cisco Unified Communications Manager, Release 15 and SUs - Integrate Cisco Applications](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cucm/admin/15/systemConfig/cucm_b_system-configuration-guide-15/cucm_b_system-configuration-guide-14_chapter_011000.html), Integrate Cisco Applications > Cisco Unity Connection (SCCP protocol). Checked 2026-09-25. [^51]: Unified CM documents that a SIP integration with Unity Connection uses a single trunk per Unity Connection server and removes the need to configure directory numbers for voicemail ports and MWI. Source: [System Configuration Guide for Cisco Unified Communications Manager, Release 15 and SUs - Integrate Cisco Applications](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cucm/admin/15/systemConfig/cucm_b_system-configuration-guide-15/cucm_b_system-configuration-guide-14_chapter_011000.html), Integrate Cisco Applications > Cisco Unity Connection. Checked 2026-09-25. [^52]: In Unified CM, the Accept Unsolicited Notification field of a SIP trunk security profile makes Unified CM accept incoming non-INVITE unsolicited notification messages that arrive over the SIP trunk. Source: [Security Guide for Cisco Unified Communications Manager, Release 15 and SUs - Trunk and Gateway SIP Security](https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cucm/security/15_0/cucm_b_security-guide-release-15/cucm_m_trunk-and-gateway-sip-security_reog.html), SIP Trunk Security Profile Settings, field 'Accept Unsolicited Notification'. Checked 2026-09-25. [^53]: Per-line MWI in the Webex App multi call window on Unified CM requires Unified CM 12.5 SU6 or 14.1 SU1 onwards. Source: [Configure multi call window for Calling in Webex App (Unified CM)](https://help.webex.com/en-us/article/l8xf9l), Prerequisites. Checked 2026-09-25. [^54]: For Webex App calling on Unified CM, voicemail and MWI rely on Cisco Unity Connection being integrated with the Unified CM environment. Source: [Configure multi call window for Calling in Webex App (Unified CM)](https://help.webex.com/en-us/article/l8xf9l), Configure Voicemail and MWI. Checked 2026-09-25. [^55]: When a Webex Calling user's voicemail uses an external mailbox, all messages go to the specified email address and cannot be accessed by phone, Webex App or User Hub. Source: [Configure and manage voicemail settings for a Webex Calling user](https://help.webex.com/en-us/article/hc69wk/Configure-and-manage-voicemail-settings-for-a-Webex-Calling-user), Manage a user's voicemail message storage, Use external mailbox. Checked 2026-09-25. [^56]: Because an external mailbox sends Webex Calling voicemail to email rather than to a phone-accessible mailbox, a user on external storage should not be expected to see a normal phone MWI unless the new-message indicator option is available and set for that storage mode; this should be checked before treating a dark lamp as a fault (inferred). Source: [Configure and manage voicemail settings for a Webex Calling user](https://help.webex.com/en-us/article/hc69wk/Configure-and-manage-voicemail-settings-for-a-Webex-Calling-user), Manage a user's voicemail message storage. Checked 2026-09-25. [^57]: In Control Hub, a Webex Calling user's voicemail message storage settings include a 'Use new message indicator on phone' option to enable the phone's new-message indicator. Source: [Configure and manage voicemail settings for a Webex Calling user](https://help.webex.com/en-us/article/hc69wk/Configure-and-manage-voicemail-settings-for-a-Webex-Calling-user), Manage a user's voicemail message storage. Checked 2026-09-25. [^58]: Cisco's technote 'Troubleshoot Voicemail Issues in Webex Calling' (April 2024) covers voice portal, voicemail enablement, extended away greeting, PIN reset and transcription but contains no MWI-specific troubleshooting procedure. Source: [Troubleshoot Voicemail Issues in Webex Calling](https://www.cisco.com/c/en/us/support/docs/unified-communications/webex-calling/221890-troubleshoot-voicemail-issues-in-webex-c.html), whole document (section list). Checked 2026-09-25. [^59]: For a Webex Calling voicemail group set up with a virtual line, a new voicemail turns on the MWI on the devices that the virtual line number is assigned to. Source: [Manage a shared voicemail and inbound fax box for Webex Calling](https://help.webex.com/en-us/article/mcjd4u/Manage-a-Shared-Voicemail-and-Inbound-Fax-Box-for-Webex-Calling), Create a voicemail group with MWI using a virtual line. Checked 2026-09-25.