* as a Least Cost Router and hybrid pbx

Hello all,

Longtime lurker, firsttime poster.

We have a Mitel SX200 PBX in place right now. We’re adding 3 branch offices and they want to “have them on the PBX”, but don’t want to sink any more money in to the SX200. It also has an external VM system connected using trunks and SMDI.

We also have a PRI from the ILEC as well as a dedicated LD T-1 (going away to switched LD).

I’ve played with *@Home and been impressed. So, my thought is to expand the phone system using * and I wanted to tap the collective knowledge of the group to see if I’m on the right track.

  1. If I were to put a Digium PRI card in between the ILEC PRI and the SX200, could I route all LD traffic from the SX to the * box and have it then LCR the traffic (we’ll have analog trunks in the remote locations) either down the PRI or out the remote office?

  2. Assuming we do 1, can the Digium lock clock off of the ILEC and supply that clock back to the PRI facing the SX so we’re in sync to avoid slips?

  3. Can I set * up to be the VM system for the SX users and route their access to the VM down the PRI tie line? Is * SMDI implementation functional enough to allow that?

  4. If I put analog FXO gateways out in the remote offices for local trunks/911, can SIP and * properly supervise the line so we don’t run in to glare issues, or do I need to use a differen protocol to manage that aspect of it?

  5. As an alternative to remote analog GW’s, has anyone successfully used multiple SIP trunks from Teliax or Vonage? Teliax can give us local numbers, but can * make the distinction between them to route calls LCR down the proper SIP trunk?

Basically, I want to leave the PBX in place, move to * VM for the existing users and bring all new phones up as SIP phones here and at the remote offices. I’m looking for some real world experiences before we go down this road. I’ve worked with * in the simple world or Zaptel POT’s lines and an IAX trunk, but I want to make sure it can function as a decent softswitch before I get egg on my face.


  1. i believe so, it sounds like you just want to insert the asterisk box between the PSTN and your legacy PBX to have additional routing options - this is very common and should work fine.

  2. yes, if you have a PRI coming and another going out (on the same card, say a 2 port digium card) you can sync the first port off of the telco and have the second port act as the master for the legacy PBX. this is also very common and should work fine.

  3. yes, it’s all in the dialplan, should be very simple.

  4. yes, again, all in the dialplan and how you route calls.

i think what you are trying to do is very common, although i’ve never had to integrate asterisk with another PBX. however, because of the immense flexibility in asterisk, almost anything is possible.

hope this helps.

Thanks for the quick answer. I think we’ll chase it down.