A customer of mine has a SIP trunk connecting their PBX to Telco (Japan NTT). As they are migrating telephony to Cisco CUCM, we are putting a CUBE to connect Cisco IPT to Telco.
However, after consulting with customer, we learned that:
- PBX ip address (the interface connected to NTT) is dynamic, provided by their DHCP.
- SIP server IP address is unknown, and I guess, it should be provided in some options in DHCP.
I searched internet and found a document from Cisco: http://www.cisco.com/c/en/us/td/docs/ios-xml/ios/voice/cube_sip/configuration/xe-3s/cube-sip-xe-3s-book/voi-sip-param-dhcp.html
I tried to simulate the same in my lab but not able to have a working one, not sure if issue is at CUBE side or at simulated-Telco-side.
Do anyone have experience with this before? Any suggestion for me?
Thank you very much,
1. even PBX ip address is dynamic, provided by their DHCP it can be statically maped. so it will be the same all the time.
2. you can use loopback IP address. as a SIP address. for both signaling and RTP
3. NTT SIP server IP address is unknown ? ask NTT
I like to follow the easy way as well. but I think there should be some good reasons that dynamic SIP information provided in DHCP is recorded in some RFC. And who knows, maybe the new way will be standard in future?
In the Cisco link in my question, DHCP option 120 and DHCP option 125 are mentioned, they are for SIP server information, RFC3925 and RFC3361 are for these options.
So again, my question is not about the best way to deploy the SIP trunk (which I still think static IP is still the most suitable for now), but how to do it in a new way (with dynamic SIP information provided via DHCP).
What are you trying to simulate? CUBE to have DHCP? You shouldn't be doing that. It not advisable. The fact that the customer had this in place doesn't mean it's a good practice and this is your opportunity to address it.