Cisco 804 and ISDN problems

Question

I've got a problem that I could use some input on. We have several
Cisco 804 routers that we use for our teleworkers at home. They have
standard PC's that connect to the ethernet interface on the router
and to a Siemens phone with Optiset teleworking adaptor via 9 pin
serial cable and COM1 port on the PC.
On the router, we are running the BRI0 and Dialer1 interface with
PPP multilink. I can get the router connect to our DC here in
Seattle without problem. The problem comes while trying to use
Siemens callbridge.
With the phone connected to POTS2 and not signed into callbridge, I
can pickup the handset and get a dial tone. I then sign into
callbridge which takes the phone (via the serial cable) and connects
it to a server (over Ethernet) here in our office in Seattle. This
succeeds, however when we then go off hook while signed into
callbridge, we don't get a dial tone.
I should step back for a second and state then when not signed into
CB, and pick up the phone, we'll see the router release BRI0:2 and
give it a voice (dial tone) signal. When signed into CB, this does
not happen. We are also seeing the error below:
ISDN BRI0: isdn_is_bchannel_available: No Free B-channels
I've got ISDN Events and q931 debugging on and am not seeing anything beside the error above that would point to a problem. Cisco has a 20 page debug all that they are going through to search for an answer.
Any chance that anyone has worked with this before?
Thanks,
James

Answer 1

I would say that this is because the router is connected over 1 b channel to your seattle office and then when you log in with your callbridge you are using the second b channel so when you goto use the phone the router simply has no more b channels to use to carry your phone call which is why you get no dial tone.As BRI ONLY HAS 2*64Kbits b channels and 16Kbits d channel(signalling)