PSTN trunking for hybrid Webex Calling deployments

Publisher

Cisco Systems, Inc. (Webex Help Center)

URL

https://help.webex.com/en-us/article/x3f0tm/PSTN-trunking-for-hybrid-Webex-Calling-deployments

Published

2025-11-04

Updated

unknown

Accessed

2026-09-04

HTTP status

200

License

Cisco proprietary documentation, all rights reserved; no-redistribution; short excerpts and locators only

Source notes citing this source

• With Avaya kept in front, the carrier keeps delivering to Avaya and migrated numbers are routed from Avaya over a SIP trunk to an SBC acting as the Webex Calling Local Gateway, where they arrive as +E.164 numbers mapped to entry points. inferred in context
• In hybrid PSTN trunking, the enterprise SBC that terminates Webex Calling route groups can be any SBC supported by Webex Calling. in context
• Webex Calling PSTN trunking lets an organisation connect on-premises PBX systems to Cloud Connected Partner PSTN and to Local Gateway PSTN. in context
• PSTN trunking for hybrid Webex Calling deployments lets on-premises PBXs such as Unified CM place and receive PSTN calls through Webex Calling using Cloud Connected Partner PSTN or Local Gateway PSTN. in context
• Hybrid PSTN trunking requires an add-on Webex Calling Route List Calls license, which allows 20% bursting above licensed call volume before non-emergency calls are blocked. in context
• In hybrid PSTN trunking each route list is assigned to a single location, and the calling number sent by the on-premises system must match an E.164 number configured in Webex Calling. in context
• The calling party number in the SIP INVITE from the on-premises system must match an E.164 number configured in the Webex Calling route list. in context
• If RedSky is enabled for a route list's location, emergency calls from that route list go through RedSky; otherwise they go through the location's PSTN provider. in context
• With Webex Calling route lists, an inbound PSTN call goes to a trunk in the route list's route group when the called number is in the route list, and an outbound call from the on-premises PBX uses the location's PSTN when its calling number is in the route list. in context
• Route-list off-net calls need an add-on Route List Calls license that allows 20% bursting over the licensed volume; beyond that, non-emergency calls are blocked. in context
• Route lists for hybrid PSTN trunking support Cloud Connected Partner PSTN and on-premises PSTN through a Local Gateway. in context
• During coexistence, users still on Unified CM keep whatever emergency routing Unified CM already gives them unless their numbers are placed on a Webex Calling route list, so a phased migration runs two emergency-calling paths that each need their own testing. inferred in context
• Webex Calling PSTN trunking for hybrid calling scenarios lets an organisation connect an on-premises PBX to Cloud Connected Partner PSTN or Local Gateway PSTN, and Cisco presents phased cloud migration ahead of moving all users as one of its purposes. in context
• With PSTN trunking for hybrid deployments, on-premises PBX users can place and receive PSTN calls through a Cloud Connected Partner PSTN via Webex Calling. in context
• Integrated Cloud Connected PSTN providers supply numbers to Control Hub automatically; numbers from non-integrated providers must be added manually under Calling > Numbers. in context
• For a non-integrated Cloud Connected PSTN provider, an admin can add up to 1,000 numbers at a time and choose to activate them immediately or later. in context
• In hybrid deployments, a PSTN call is sent out on one of the trunks in a Route Group when the called number matches a number configured in a Route List. in context
• The Route List Calls bursting announcement plays only for outbound off-net calls; it does not play for inbound calls or for emergency calls. in context
• When off-net call volume exceeds the 20 percent bursting allowance, non-emergency calls are blocked. in context
• The Route List Calls license includes 20 percent bursting beyond the licensed call volume. in context
• While in bursting mode the originating on-premises user of an outbound off-net call hears an announcement that the call is in bursting mode and advising them to contact their administrator. in context
• Additional Route List Calls capacity is added to an existing subscription by purchasing the Add Route List SKU through a change order, and existing Enterprise Agreement customers need a subscription modification to obtain Route List Calls licenses. in context
• Calls blocked by Route List Calls capacity exhaustion are rejected at call admission before media is established, so troubleshooting tools that measure media quality will show no packet loss, jitter or MOS degradation for the failed calls. inferred in context
• The Route List Calls license sets the limit for concurrent off-net PSTN route list calls between an on-premises system and either cloud or on-premises PSTN. in context
• Enterprise Agreement customers receive Route List Calls capacity equal to 25 percent of their Webex Calling licensed users. in context
• Incoming calls that exceed the Route List Calls limit are rejected without an announcement to the caller. in context
• Named User customers receive no Route List Calls capacity by default and must purchase it separately. in context
• Route List Calls licensing is org-level concurrent call capacity rather than a per-user assignment, so it does not appear on an individual user's license record in Control Hub. inferred in context
• Trial subscriptions include 10 concurrent Route List Calls. in context
• Webex Calling PSTN connectivity is chosen per location in Control Hub, for example Cloud Connected PSTN or on-premises PSTN through a Local Gateway. in context

Cite this source record

APA

WarmTransfer. (2025, November 4). PSTN trunking for hybrid Webex Calling deployments. WarmTransfer. https://warmtransfer.net/knowledge/sources/cisco-help-x3f0tm-pstn-trunking-hybrid

BibTeX

@misc{warmtransfer-cisco-help-x3f0tm-pstn-trunking-hybrid,
  title  = {PSTN trunking for hybrid Webex Calling deployments},
  author = {{WarmTransfer}},
  year   = {2025},
  url    = {https://warmtransfer.net/knowledge/sources/cisco-help-x3f0tm-pstn-trunking-hybrid},
  note   = {Cisco Systems, Inc. (Webex Help Center), accessed 2026-09-04}
}