Split lines to isdn modem


i wonder if anyone has any experience with using a line splitter on an ISDN modem. The company i work at, want to replace all phone systems with asterisk servers, to make outbound predictive calls (callcenters). This has to be tested first of course, but production has to continue as usual as well.

We would like to implement one asterisk install in one of the call centers, where we have 60 lines. We would like to have about 8 agents call out predictive with trough the asterisk solution. So far so good.

Now, if i put an asterisk server next to our regular servers, connected to an ISDN modem trough a splitter and “steal” 8 lines, what will happen. I guess calling outbound will not be a problems, as long as we make sure there are not too many agents using lines trough the “old” server. We also have incoming traffic, and i wonder what happens to those incoming lines… Is there any way to tell asterisk to ignore those lines, so the “old” server picks these up? Or is there a way to tell asterisk to patch these incoming lines to the “old” server? I’m kinda in the dark about this one… So, if anyone has any advice, it would be really appreciated! The sooner it works, the sooner we will kick those other overpriced servers out the door.



The “lines” as you say only exist as timeslots in a 2 megabits per second stream of data.

To do what you want you need to either connect asterisk in the line and pick of the calls you want or have it connected to a e1 “after” the system

I have done bothe with Asterisk and many other PBX systems. and the former is the better option. Basicly you just send calls straight through or using DDI pick off the ones you want.

Ian Plain


Hi Ian,

i’m not totally sure that i understand what you mean with “connect asterisk in the line”. Could you please explain?

thank you.


cyber-cottage.co.uk/site/index.p … &Itemid=60


Totally clear, tnx alot! I use astribanks here, so i should get an astribank with 2 e1 connections to be able to relink it like this. tnx very much, i will try this one!

Hi Great

Only used astribanks for BRI and FXO/FXS but should be OK personaly I use red-fone units for E1 installations As they support redundancy realy well