Potential problems if I change DNS ip address in CUCM

[TrickTrick]

Hi,

We have a Telephony platform linked to different locations across the world via sip trunks, we have a problem with 1 site using an old system (Nortel 1k), I think the sip trunk is configured as it should be, added the normalization script, and i'm now suspecting the DNS, here's my analysis:

replaced CUCM SIP trunk with a Voice gateway sip trunk, in both situations we can make calls towards that site, but can't receive, I did a debug of SIP messages, I see in the invites received that the Nortel call manager sends : Extension@domain.com, while we send Extension@cucmipaddress... I presume the DNS is the problem and I have to change it and use the client's DNS

I want to knowif there's any potential problems if I make that change 

[TrickTrick]

can you elaborate ? thanks :)

[Chris Deren]

What is the disconnect reason code? Can you provide "debug ccsip messages" from your GW?

[TrickTrick]

here's a trace of sip debug hen I had SIP trunk configured in the VG

https://pastebin.com/7y73qGUh

[Ayodeji Okanlawon · Accepted solution]

Hi there,

This has nothing to do with DNS resolution. If CUCM is receiving "Extension@domain.com", CUCM will not process the request unless the domain is configured in either its CFQDN ( cluster fully qualified domain name) or its OTLD ( organization top level domain name). You can easily add the domain as follows:

CUCM>enterprise parameter> cluster fully qualified domain name> add the domain here...

[TrickTrick]

i'll try this and reply back, thank you

[TrickTrick]

Thank you sir, this was the solution to that particular problem for me :)