Cube config sip trunk to Deutsche Telekom

[ajber]

Does anyone have a cube config with sip trunk to Deutsche Telekom?

I have a manual from https://www.cisco.com/c/dam/en/us/solutions/collateral/enterprise/interoperability-portal/connecting-unified-communication-manager.pdf but sip settings are different (document from 2017) 

[b.winter]

Hi Ajber,

PM me, I have a complete configuration.

Best regards

[ajber]

Okay thanks, i have sent you an PM

[Roger Kallberg]

@b.winter Why do you not post the configuration here for the greater good of the community? Recommend you to remove/edit any part(s) of it that would contain personalised/corporate information before posting it.

[b.winter · Accepted solution]

Hi Roger,

maybe you are right

Config is attached to this post.

This config is for the "Standard SIP Trunk" product of Deutsch Telekom.

If you need to configure a SIP Trunk for the product "CompanyFlex" of Deutsch Telekom, this is a different configuration.

One important thing to mention:

This configuration assumes, that the CUBE has a public IP address configured on the WAN-Interface.

If you have a private IP with NAT in front (e.g. on FW), then there will be a "No-way-audio"-issue for calls coming in from PSTN, which then will be forward (CFwdAll) back to PSTN.

PSTN --> CUBE --> CUCM --> CUBE --> PSTN

This is a "specific" behaviour of the SIP-plattform used by Deutsch Telekom (and other (german) providers).

Solution:

1: MTP on SIP Trunk in CUCM (easiest, but not a good solution)

2: add STUN config on CUBE

3: add "media anti-trombone" under "voice service voip" on CUBE

If anyone, who reeds this post, has questions about the config, just drop me a PM

Best regards,

Björn

[Roger Kallberg]

Thank you! ':-)'

[b.winter]

Would be awesome, to get my first solution

[Roger Kallberg]

Well deserved! Let's hope @ajber markes it as solved.

[ajber]

Thank you very much. I now also understand there is a difference in legacy sip-trunk product and new companyflex product. Both have different configuration settings. Appreciated your help!

[reindl_mc]

Hi Björn,

can you also share your config for "CompanyFlex" SIP Trunk ?

Greetings from Austria, Bernhard

[b.winter]

Hi Bernhard,

sorry, was on holiday.

Config is attached.

Please keep also my mentions for the other config in mind.

Greetings back to my old company

[reindl_mc]

Hi Björn

great document, thank you very much.

kind regards

Bernhard

[jacky.reinbold]

Hello Bjoern,

This Company Flex config seems to be outdated when not using a dedicated Telekom access, as TLS seems to be mandatory now, which is badly documented.

Would you have a working configuration with description as you've posted it for the other telekon variants?

Thanks a lot,

Jacky

[b.winter]

Hi Jacky,

yes that's true. If the internet connection is not from Telekom, TLS/sRTP is mandatory.

"outdated" is good, I have never seen a secure config in all the info I've gotten ':D'

CA-Cert from Telekom can be downloaded here, it's the "T-TeleSec GlobalRoot Class 2"
https://www.telesec.de/de/root-programm/informationen-zu-ca-zertifikaten/root-zertifikate/

Attached is a text file with the config changes to be made.

[jacky.reinbold]

Hi Bjoern,

Thank you for your reply, but I could make a working config just in time for my project, but will compare to your config.

I mean "outdated" because the technical document for CompanyFlex provided by Telekom schould not be an earlier Version than 04/22, because both options, secure/unsecure were possible in the past.

I've seen that you've described a common issue, the lack of RTP/audio transmission and call interruption by PSTN > CUCM/Phone> PSTN (mobile) CFWD, with clip no screening enabled, of course.

What's your own recommended and most consistent method to resolve this ever returning issue ?  A STUN config as best method?

Cheers,

Jacky