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PRI details

just wondering if someone can answer my questions re PRIs----

-from a Cisco router, how do I find out how many PRIs are at a site? Is there any other Cisco tool available to find this out?

-if there are 5 PRIs on a site, how can I find out number of calls on each PRI on a given time?

-Can you bounce or move active calls from one PRI to another? not sure if this is even possible!!! Thanks

Georg Pauwen
VIP Expert



I have never heard of a tool that shows all available PRIs (on different devices I assume)...the command 'show isdn status' only shows you the interfaces connected to the device this command is executed on...


As for 'bouncing' calls from one PRI to another, are you referring to ISDN PRI PPP Multilink ?

Giuseppe Larosa
Hall of Fame Master

Hello @G3261 ,


show isdn status can tell you how many ISDN circuits are in the local router as noted by Georg.


About call history you can use


show isdn history


moving an active call to another PRI might be not possible . moving next  outgoing call to another PRI is possible if the resources are shared in a pool of a PRI if the first PRI has ended the B channels the next call can go out another PRI.

Another way to manage multiple PRI in multiple routers is using CUCM Call Manager if it manages all the voice gateways via MGCP.

In CUCM you can create an ordered list of outgoing PRI interfaces to be used to place a call ( route list )


Hope to help



Scott Leport



Just to add to the advice given.


"show isdn status" will tell you how many ISDN circuits you have AND if it's operational (MULTIFRAME ESTABLISHED etc).

"show voice call status" and "show voice call sum". The former tells you how many calls are active and the latter will tell you which channel is being seized for the call.

Not aware of a way to "bounce calls" to another PRI. As Guiseppe mentioned, you can use Route List / Route Group configuration in CUCM to influence outbound call routing from CUCM -> Gateway -> PRI, but that wouldn't control inbound call routing. That part would be down to the carrier and how they would handle failover to another PRI.

Also, assuming we're talking about one gateway and many PRI's, CUCM RG wouldn't help you here, but possibly trunk groups might.

That's been discussed once or twice on this forum:


thank you all for your input and guidance...much appreciated!

Scott, I figured out I have 3 PRI by using sh isdn status command. Is there a way for me to check if there are any LIVE calls on one of the serial ports individually?

0/0/0 - 0/1/0 or 0/1/1?

Hi G3261,


Apologies for my late reply, not been on here recently.


Assuming you haven't already figured this one out, you can issue the command "show voice call summary" and you'll see live calls and which channel is seized.


Hope this helps, all the best.



no worries....thanks for getting back. just curious, when I do this command I see example-0/1/0 1 - 23 Shut Down. What is that means? Most of them showing - besides port numbers that means there are no calls on these port yet?

Hi there,


Do you mean its showing down / down on a show ip int brief?


Yeah, the B channels will stay down and will only come up if there are calls. The D channel however will remain up. Not sure which country you're in, but the D channel will be either Serial0/0/0:15 or Serial0/0/0:23. Every other port on the PRI in between will be B channels.

something like this...I am in Canada