PRI Trunking BCM50 and Cisco ISR 2851
This is something I struggled with for a long while, yet the fix is rather simple. For whatever reason, the BCM50's Q.931 implementation does *not* like the Cisco sending the "CONNECTED NUMBER" information element. It took me a while to figure this out, but when I did...boy was I happy.
Configure the BCM's PRI as follows:
Trunk type: PRI
Configure the Cisco's D channel as follows (example):
The key is setting "no isdn outgoing ie connected-number" on the PRI facing the BCM. If you don't do this, you will find that the BCM will receive calls over the PRI without issue, but placed calls will drop with "Invalid IE" as soon as they supervise. Setting "isdn supp-service name calling" enables calling name display, which is nice to have. Without this, all you'll get is the calling party number.
UPDATE 2021-01-17: I ran into a situation where when the far side returns the called party's display name (not common, but is possible), the BCM50 "wigs out" and dumps the call. Simply adding "no isdn outgoing display-ie" fixes this. I have updated the D channel config above to reflect this.
And, with that, you have a fully functioning PRI trunk!