CallManager with 2 T1s (NFAS) limited to 23 calls (should be 46)

Unanswered Question
Jun 6th, 2007

Our CallManager is using a gateway configured with 2 T1s. The T1s are in NFAS configuration, 1 Primary D channel and the other is a Backup D channel. In total, we have 46 B channels available for PSTN calls.

If I run "sh voice call stat", it shows me the correct number of Active ISDN calls. If I run "sh isdn serv", it shows that calls are spread between the 2 T1s (so NFAS configuration is working). If I run "sh isdn nfas group 1", it shows the correct number of available B channels (46 minus number of Active Calls).

In CallManager, Route List is configured to use PSTN Route Group and if all channels are used, it will failover to using VOIP (Gatekeeper).

Problem is eventhough we have 46 B channels, we can only make 23 simultaneous ISDN calls, the 24th call uses VOIP. We're supposed to have 46 calls but it seems CallManager is recognizing the NFAS as 1 T1.

Any ideas? Thanks.

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thisisshanky Wed, 06/06/2007 - 19:54

i would recommend that you shut down primary t1 to see if you are able to place calls through backup t1. If this works, then can you paste your configs (dial peers).

junp14 Wed, 06/06/2007 - 20:47

Primary was shut down and I was able to place calls on the Backup T1.

Here are the dial-peers:

dial-peer voice 9000 pots

call-block translation-profile incoming block_fax

call-block disconnect-cause incoming call-reject

destination-pattern .T

incoming called-number .

direct-inward-dial

port 0/0/0:23

!

dial-peer voice 2000 voip

destination-pattern 2...

progress_ind setup enable 3

modem passthrough nse codec g711ulaw

session target ipv4:10.10.10.1

incoming called-number .

dtmf-relay h245-signal h245-alphanumeric

no vad

!

dial-peer voice 3000 voip

destination-pattern 3...

progress_ind setup enable 3

modem passthrough nse codec g711ulaw

session target ipv4:10.10.10.1

incoming called-number .

dtmf-relay h245-signal h245-alphanumeric

no vad

!

dial-peer voice 7000 voip

destination-pattern 7...

progress_ind setup enable 3

modem passthrough nse codec g711ulaw

session target ipv4:10.10.10.1

incoming called-number .

dtmf-relay h245-signal h245-alphanumeric

no vad

Thanks.

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