Seeking advice - moving from old AltiGen PBX to Asterisk


Please accept my appologies - I’ve been reading through the handbook and the online documentation / mailing list archives as well as the forum here and can’t quite get my own answer to these inquiries… The biggest mystery is how the existing handsets are connected to a new machine running Asterisk.


  • Our phone system we have is horribly out of date and may pack-it-in any day now.
  • Existing PBX system (AltiReach running on NT4) but we plan on replacing this server entirely and ditching the old PCI cards but keeping the hand sets (approximately 30 Nortel hand sets).
  • We have 12 regular phone lines coming into this system (are these called PSTN lines?)
  • We have satelite offices that could be VOIP after the system is implemented - this is a secondary priority at this point though.

What is the best hardware configuration for this? Should we get a T1? Do we have to? Which cards/hardware should we use? We are currently unclear on how the hand sets connect to the system but moderately clear on how the phone lines would connect to the box. Some information sources or direct examples of how to switch from a 30 handset office to an Asterisk system with those same handsets would be awesome. Once we replace our current setup we will delve into the extended features/options available. VOIP is probably the most important one after we switch systems entirely. Ultimately I think we plan on having the phone systems coexist for a while during the migration to Asterisk (once its working on a few of our 12 phone lines).

If there is anything else I can provide to help you help me I will reply as soon as possible.

Thank you!

A few points:

  • A T1 is not necessary as there are possibilities of using a Channel Bank or various analog solutions
  • Your Nortel phones may or may not be useable, depending on if they are proprietary digital handsets (no) or analog ones (yes)

System sizing is an imperfect art, but a good place to look to get an understanding is here and here. Of course it is necessary to understand how you plan to use the system in order to begin to scope the hardware, such as:

  • Maximum number of concurrent connections (12 + internal)?
  • Percentage of traffic that you will do compression with (ie - GSM, Speex, G729, etc)?
  • How intensive will you need to be with your dialplan logic?
  • If you decided to use internal hardware (PCI cards say from Digium) will you be using echo cancellation?
  • Will the system provide conferencing facilities?
  • Etc

Also, I recommend picking up a copy of this book:

Asterisk - The Future of Telephony