Log In

Come Join Us!

Are you a
Computer / IT professional?
Join Tek-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Tek-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here


PRI trunk between BCM50 and Cisco 2851

PRI trunk between BCM50 and Cisco 2851

PRI trunk between BCM50 and Cisco 2851

In my lab I have a BCM50 trunked with a Cisco 2851 via PRI. The Cisco 2851 acts as a "tandem" of sorts which gives the BCM access to other telephony stuff on the network.

Something I've been banging my head trying to figure out is how to configure the trunk between the BCM and the Cisco to support the display name information element (IE). It kind-of works which I will explain...

I have other telephony things that trunk with the Cisco. When those devices send a call to the BCM via T1/PRI, CLID works as expected. Along with acting as a T1/PRI tandem of sorts, the Cisco also has some FXS/FXO interfaces that I use for various things. If I initiate a call from an FXS or FXO interface to the BCM, the station the call is destined for rings for a blip and the CLID information is transmitted as expected but the call is quickly rejected with a cause code indicating an invalid IE. This is using the DMS-100 switch type. I've heard that Cisco's implementation of the DMS-100 ISDN spec can be problematic (though this is the first I've had any issues as it's my go-to switch type in the lab), so I experimented with other switch types, and here's where things get weirder.

If I use National switch type (so NI-2 on the BCM and primary-ni on the Cisco), the BCM can receive calls but only the calling number. I discovered that this is because the Cisco does not send the display name IE by default with switch types outside of DMS-100. So, I configured "isdn supp-service name calling" on the Cisco side and lo and behold we get the calling name AND display name! But...

When the Cisco is set to switch type National, the BCM cannot originate calls. The calls will get to alerting, but as soon as the call is answered thus a CONNECT message is sent, the call is immediately released with a "Message not compatible with call state" cause.

I can make things happier by setting the switch type on the Cisco side to 5ESS (and leaving the BCM as NI-2), but only if I disable the display name IE. I can also set both the Cisco and BCM to switch type 4ESS, but it doesn't appear the BCM supports the display name with that switch type. Even with the Cisco sending the display name IE the BCM seems to ignore it...though I could be doing something wrong.

Any ideas would be greatly appreciated!

I can post some Q.931 debug stuffs upon request if anyone thinks it'll be useful, just let me know.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Tek-Tips Forums free from inappropriate posts.
The Tek-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Tek-Tips forums is a member-only feature.

Click Here to join Tek-Tips and talk with other members! Already a Member? Login

Close Box

Join Tek-Tips® Today!

Join your peers on the Internet's largest technical computer professional community.
It's easy to join and it's free.

Here's Why Members Love Tek-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close