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C2650 PRI problem


Hi all. We have Cisco 2650 with PRI channel. It connects to the PBX and then to PSTN. Signalization type between PBX and Cisco - primary-net5 (EDSS-1).

There is one problem. Some people calls to our gateway Cisco, it tries to deliver these calls to PBX.

Because of some reasons answer from PBX comes in 16 seconds. C2650 waits during 10-12 seconds and finish call.

What should I do to make Cisco wait more than 16 seconds?

Debug for call in attachment.

sh isdn timers:

ISDN Serial1/0:15 Timers (dsl 0) Switchtype = primary-net5

ISDN Layer 2 values

K = 7 outstanding I-frames

N200 = 3 max number of retransmits

T200 = 1.000 seconds

T202 = 2.000 seconds

T203 = 16.000 seconds

ISDN Layer 3 values

T301 = 180.000 seconds

T303 = 40.000 seconds

T304 = 30.000 seconds

T305 = 30.000 seconds

T306 = 30.000 seconds

T307 = 180.000 seconds

T308 = 4.000 seconds

T309 Disabled

T310 = 20.000 seconds

T313 = 4.000 seconds

T316 = 120.000 seconds

T318 = 4.000 seconds

T319 = 4.000 seconds

T322 = 4.000 seconds

T3OOS = 5.000 seconds

TGUARD= 17.000 seconds, Expiry = REJECT_CALL

6 Replies 6


Well, you better find out why the PBX sends back an ALERTING message after so much delay. Is the called party directly connected to the PBX, or the PBX is routing this call transit to another PBX/PSTN switch ?

Is the called party a mobile/GSM user ?

Ok, really I know that PBX connects to another PSTN switch and technical support told me that there are many protocol transformations (from EDSS-1 to SS7 and others) and they could not decrease delay between CallProceeding and Connect.

Called party is common PSTN user. We have to configure our equipment ih such way because of configuration of our partners.

Indeed, you are not getting a "CALL Proceeding message".

On the debug I see how Cisco sends a SETUP message and after 12-13 seconds receives an ALERTING message from the other side. Then I do not see a RELEASE_COMPLETE message (or CONNECT). Run a debug once again and post it.

Does the calling party hear the "ringback" ?

CALL Proceeding Cisco sent to the originating gateway. From PBX Call Proceeding didn't come.

Debug in attachment.

Dude, I do not see anything wrong on your last debug. The PBX (the remote side) sent an ALERTING message within one second after your Cisco has sent the SETUP. And then your Cisco has sent a RELEASE COMPLETE.

Thanx for help. There was a strange way for solving this problem: copying old config, reloading gateway, and setting up isdn timers. :)

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