It looks like VOIP traffic to PSTN lines might very well be taxed in
> the near future. One thing that this does is encourage institutions
> with their own PBX's to keep as much traffic as possible from hitting
> the PSTN by routing eligible traffic over private lines. One
> interesting method is to tie all participating PBX's together via the
> internet using globally unique "tie-line" numbers.
Yes, it's godsend for the private PBX's. Here is the Q&A from the FAQ which might help the new users planning for the trial, which actually needs little or no modification of your existing system.
-- Q. Can you recommend an inexpensive VoIP-capable platform?
A. If your existing PBX has the ability to take as inputs a PRI, FXO, or FXS line(s), then it is possible through inexpensive hardware and free software to create a gateway to existing TDM infrastructures for both outgoing and incoming calls. If you have an old Pentium II 400mhz or better system as a spare, it may cost as little as $20 to create a gateway platform with Asterisk that integrates a single FXO trunk into your existing PBX. PRI-capable systems can use the same (or slightly better) CPU hardware, and single-PRI cards are in the $500 range.
Raqueeb Hassan Bangladesh