Cisco Cube - SIP - T-Mobile Company Flex Service

[msasala]

We recently had to move from an ISDN Hand-Off to a SIP Based Service from T-Mobile called Company Flex

I was able to find a guide from another post, https://community.cisco.com/kxiwq67737/attachments/kxiwq67737/discussions-uc-infrastructure/168390/1/Telekom%20Company%20Flex%20DE.pdf

I am not able to get the SIP Trunk to register to tel.t-online.de

It looks like the A record for them was replaced with an SRV record, but im not sure what would need to be done from the CUBE side to setup a connection to the SIP Domain.

[Roger Kallberg]

Could you please post your current configuration and any specific information that you have got from your service provider?

[Elliot Dierksen]

You aren't registering with the provider because there is no "sip-ua" block that tells the router to do so. Something roughly like this.

sip-ua
 credentials username 5555551234 password 0 My-secret-password realm registrar.myprovider.com
 authentication username 5555551234 password 0 My-secret-password realm registrar.myprovider.com
 registrar dns:registrar.myprovider.com expires 60
 sip-server dns:registrar.myprovider.com

The "dns:" argument is referencing a DNS SRV record. See an explanation here.

https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/voice/cube/configuration/cube-book/voi-cube-sip-dns-srv-rfc2782.html#id_99479 

[Roger Kallberg]

From what I saw he is doing the registration in a tenant configuration, with this there is no need definite this in the sip-ua.

[Elliot Dierksen]

Thanks @Roger Kallberg , I missed that. I think you don't need the "@tel.t-online.de" in the user ID for registration since that domain is already specified in the "realm". Perhaps that is why the registration is failing.

[msasala]

i have this in now, still not able to register

voice class tenant 2000
registrar dns:tel.t-online.de expires 480 tcp
credentials number +49199296000000449050 username +49199296000000449050@tel.t-online.de password 7 10640E0A074519055D realm tel.t-online.de
authentication username +49199296000000449050@tel.t-online.de password 7 04710C150D73474058

[Roger Kallberg]

T-Mobile support should be able to help you out verifying your settings for the registration. Have you checked with them?

[msasala]

I emailed them yesterday and still waiting for a reply, i had a hard time find contact info.

[msasala]

i added this with no luck
ip host _sip._tcp.tel.t-online.de srv 1 50 5060 TMobile1
ip host _sip._tcp.tel.t-online.de srv 1 50 5060 TMobile2
ip host _sip._tcp.tel.t-online.de srv 1 50 5060 TMobile3
ip host TMobile1 194.25.0.60
ip host TMobile2 194.25.0.68
ip host TMobile3 194.25.0.52

[Elliot Dierksen]

I wouldn't hard code those SRV records. You would be stuck if they change. You should add some DNS servers to the router. Add at least two DNS servers.

ip name-server X.X.X.X
ip name-server Y.Y.Y.Y

[msasala]

I did have some in there, but i was trying to see if i had just theirs if it would allow me to ping tel.t-online.de. I just re-added the local ones i had in before. Now if i try to ping tel.t-online.de i just get "Unrecognized host or address, or protocol not running."

[Roger Kallberg]

Have you turned on DNS resolution in your gateway?

ip domain lookup source-interface GigabitEthernet0/0/0

You'll need to use source-interface if you have multiple interfaces and want to control what int to use for name resolution.

[msasala]

We just have one interface on the voice router

[Roger Kallberg]

That is a sort of an odd setup for an SBC as you would not get an inside and outside interface for the demarcation between your internal network and the service provider network. I know it works in theory, but still it is a somewhat goofy setup. I would actually recommend you consider changing this so that you have two interfaces as that gives you a much clearer demarcation point and IMHO a much easier system to maintain and not to forget troubleshoot in the long run. Based on your shared configuration earlier I think that you source the traffic to the SP from a loopback interface, if that is so you might as well just use a physical interface, with that IP set on it, on the SBC and connect that to the SP provided equipment/connection.

[Roger Kallberg]

I agree with @Elliot Dierksen it is a bad idea to hard code these name entries. It’s much better to use a DNS service to resolve these names.