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Using multiple ISDN lines?

Tomasz Bres


I've problem with setup Cisco 2811 Router to use different lines for each IP Phone.

Two ISDN BRI lines are connected and 8 numbers are available.

It's not a problem with direct call to each phone. Problem is, that every phone uses one output number.


Phone with number 45 is available form PSTN network under 749-XX-45.

Phone with number 45 should use line 749-XX-45 for outgoing calls, but it uses 749-XX-40. All phones in network do that.

What configuration points should I check to solve this problem?


7 Replies 7

paolo bevilacqua
Hall of Fame
Hall of Fame

To direct individual phones to individual lines, you need to use COR or number translation.

Since it is not a trivial configuration, I recommend you engage a reputable consltant or certified cisco partner, to have it done.

Yep, I know it.

It's funny, but it was working well and suddenly stopped.  No one know when cause from our side nothings changed. Phones works, but other side see only one number no meter which phone is calling.

Maybe telco intervened and put all the lines under an hunt group.

The first thing to do is to take "debug isdn q931" and "term mon".

In any case, leave everything to a professional. He will easily solve that, and the other tens of little things that always have to be done.

I'm just trying to understand the nature of the problem

In debug I have:

Calling Party Number i = 0x0080, '45'
Plan:Unknown, Type:Unknown

Called Party Number i = 0x80, '517XXXXXX'
Plan:Unknown, Type:Unknown

What does it mean?

Some time ago the calling spec has changed. Before I had to use "0" (zero) before number for example to call mobile i had to call 0517XXXXXX. Now zero is forbiden.

Could it be the problem?

No, Telco is rewriting the number.

It is correct that 0 had been eliminated as not necessary.

Engage again the professional that installed the system and he will sort out everything for you. Or, choose a new one.

Telco doesn't rewrite number. It's only inform with voice message "Zero is now forbidden, call again without zero at the first place" Strange Telco.

And the guy who establish this system is no longer employer of this company and he's not available

Telco rewrites calling number.

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