topic Re: Webex Registration Domain in Webex Calling

Webex Registration Domain

hs08 — Wed, 16 Jul 2025 23:56:15 GMT

I was successfull make trunk from webex to local gateway.

In the webex i can see Registrar domain and outbound proxy address, then if i lookup manually both address is not resolved.

So how actually my local gateway can connect to the webex using registrar domain provided by webex and registration was successfull even the address can't be resolved?

Re: Webex Registration Domain

Jonathan Schulenberg — Thu, 17 Jul 2025 09:38:12 GMT

SIP is designed to use DNS SRV records to find the A record(s) with the priority, weight, and listen port of each A record.

Fun fact: The destination-pattern dns: command is designed to query for an SRV record. You’re supposed to suffix the listen port if you want CUBE to query for an A record directly.

session-target dns:server.domain.tld looks for SRV first and falls back to A if that fails.

session-target dns:server.domain.tld:5060 looks for an A record.

Re: Webex Registration Domain

hs08 — Fri, 18 Jul 2025 03:48:50 GMT

Actually i tested using mxtoolbox to query the SRV record and not found.

Re: Webex Registration Domain

Jonathan Schulenberg — Fri, 18 Jul 2025 14:22:40 GMT

That's not how SRV records are formatted. A little research will help but specific to SIP, the service can be "_sip" or "_sips"; the latter is supposed to be indicate TLS security.

The example below returns two DNS A records:

dig -t srv _sips._tcp.ch06.sipconnect-us.bcld.webex.com

; <<>> DiG 9.10.6 <<>> -t srv _sips._tcp.ch06.sipconnect-us.bcld.webex.com
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 11793
;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1232
;; QUESTION SECTION:
;_sips._tcp.ch06.sipconnect-us.bcld.webex.com. IN SRV

;; ANSWER SECTION:
_sips._tcp.ch06.sipconnect-us.bcld.webex.com. 300 IN SRV 10 50 8934 sse-b6.public.wdfwwxc-p-2.prod.infra.webex.com.
_sips._tcp.ch06.sipconnect-us.bcld.webex.com. 300 IN SRV 5 50 8934 sse-b5.public.wjfkwxc-p-2.prod.infra.webex.com.

;; Query time: 37 msec
;; SERVER: [REDACTED]
;; WHEN: Fri Jul 18 10:15:30 EDT 2025
;; MSG SIZE  rcvd: 205