VTC environment CUCM + Expressway C/E + ISDN Gateway 3241

[systemtechnik1]

Hi Guys,

we are trying to install a VTC environment with following products CUCM (11.5) + Expressway C/E (8.11) + ISDN Gateway 3241 (2.2). At the moment the ISDN-GW is registrated at the Expressway-E as H.323 GW.

For this connection we have to use a isdn gateway cause there's no IP based opportunity. Now we have following problem to establish the connection:

On the SX80 codec we see a "calling" - the other side is able to answer the call but no connection is etablished. If the other side cancel the call, the codec get this feedback.

Did someone have any ideas regarding this problems?

The Expressway-C is connected via SIP-Trunk to CUCM and a SIP Route Pattern is set.

[Anurag Srivastava]

Hi,

Is there any reason that you are registering your ISDN gateway on Expressway-E? I am asking because due to this you need to open media ports on firewall between Exp-C and E. If you register on Exp-C so there will be no firewall in path which can cause no media issues.

As you mentioned it seems signalling is fine but there is media issues and for that you can take diagnostics logs on  both expressway and logs and pcap on ISDN gateway to check whether ISDN gateway is receiving the media or not and whether it is sending to Exp- E and C or not?

Thanks

Please rate if it is helpful...

[systemtechnik1]

Hi,

thanks for your reply.

We also tried to registering the ISDN gateway on the Exp-C, the problem stays the same. We send the "Invite", but don't receive a "Ringing" back.

We take our prefix with a number lets say

Prefix: 055

Prefix City: 040

Number: 12345

Our call string on the SX80 looks like: 055 040 12345

The Phone with the Number 040 12345 receives the call, can answer it, but the codec still stays in status "calling" - so there's no feedback and no active connection.