Existing PBX and Long Distance. What can Asterisk do?

I did a few searches and did not find the answers I am looking for. I am a Cisco / Microsoft engineer, but new to Asterisk, just started looking at it today.

My company has a Siemens 9751 (20 years old or so) existing phone switch, two long distance T1s, and maybe 500 phone lines. We do not have Ethernet everwhere where there is a phone, and it would be difficult to change that, so internal use of Asterisk may not be viable right now.


My question is… Can I use Asterisk to off-set our external long distance charges using VOIP to potentially augment or replace our long distance T1s? We have a business class Road Runner circuit providing about 15Megabit of Internet access that we are not fully using, and I would like to leverage this.

Thoughts please?



Hello Michael,

From my experience with Asterisk I say your plan is possible and my advice will be to investigate if you could connect your existing PBX to an Asterisk server using T1 connections (I am not an expert to Siemens - Asterisk interconnection but probably somebody have already done it and made a report) . Thus you will reuse your T1 ports on the PBX and add one T1 card into the Asterisk server.

After this, my second advice is to buy one card with 2xT1 ports, install it in the Asterisk server and play with it (PRI,VoIP,dialplans,etc).
Second test will be to take one long distance T1 and connect it to Asterisk and from Asterisk back to your old PBX
After this step you have tested that Asterisk could replace your long distance provider and you could now add VoIP routes to PBX through one T1
Last step - running on both T1s and say good bye to your provider (or not - in case you need a fall back route).


Thanks for the response. I understand building the server and using it as an interim between the phone switch and my ISP. I am looking for perhaps some sort of blueprint or guide that would be able to explain exactly how to do this. Also, would I still need a service provider for my VOIP? How do I connect my long distance into the cloud?

Any help is appreciated… Thanks.


Something for begginers:
Asterisk The future of Telephony .pdf
official documentation