T3 · T3-R04
Local gateway toward Webex Calling
Learn it in 5 minutes
- The local gateway is how premises PSTN or a PBX meets Webex Calling.
- Signaling to Calling is SIP over TLS. Media is SRTP.
- Registration-based and certificate-based trunks are different models.
- Dial peers still decide the premises leg.
- Confirm call caps and ciphers in the current guide.
Visual
What is going on
Cisco's Webex Calling local gateway documentation describes CUBE as the supported trunk on the premises side for this design. A registration trunk and a certificate trunk do not have the same limits. People quote a 250-call registration cap from older guides. Treat that number as something to confirm in the guide for your tenant before you design to it.
Confirm before relying. Confirm the current registration call cap, cipher suite, and supported platforms in Webex Help.
Worked example
A location uses a local gateway. Inbound DID hits a Webex dial peer, and outbound PSTN hits a carrier peer. If you only debug one peer, you will explain the wrong leg.
Quiz
1. A local gateway registration is the same object as a CUCM phone registration.
False. It is the trunk from CUBE toward Calling.
Ecosystem
Sister pieces sit on the ecosystem page: the glossary, the mind map, the integration map, and the sibling labs.
- Local gateway — The premises SBC that connects Webex Calling to PSTN or a PBX.
- Certificate trunk — A trunk that authenticates with a certificate instead of a registration.
Config. Keep the Webex peer and the carrier peer in the drawing.
Troubleshooting. If Calling shows the gateway offline, check registration or certificate status before the carrier.
Bridge. This is the usual bridge during a CUCM to Calling migration when the PSTN stays on premises.
Mind map, sister technologies, and future hooks live on the ecosystem page.
Sources
Product screens move. Confirm the guide for your release before you change a live system.
Sources and go deeper
Opened 2026-10. A row marked confirm has no link, because that page was not verified.
- Webex. Get started with Local Gateway last checked 2026-10
- Webex. Configure Local Gateway on Cisco IOS XE for Webex Calling last checked 2026-10
- Webex. Get started with Webex Calling last checked 2026-10
- Protocol and ports. Port reference for Webex Calling last checked 2026-10
- RFC. RFC 3711, SRTP last checked 2026-10
- RFC. RFC 3261, SIP last checked 2026-10
- Cisco. Cisco Unified Border Element product support last checked 2026-10
- Community. Cisco Community, Collaboration knowledge base last checked 2026-10
- Wikipedia. Voice over IP (Wikipedia) last checked 2026-10