[Asterisk-Users] Dual PRI fail over

[Kevin P. Fleming]

Tom wrote:
> 
> I currently have a single PRI however we are getting a second PRI, and the
> provider (qwest) wants to know if our PBX supports GSAS (they say its a
> redundant d-channel technology but searching on google for GSAS reveals less
> than nothing).  I've set something similar up before on a cisco 5350, where if
> one of the PRIs fails, all of the calls destined for either PRI will be routed
> down the one that didn't fail.  Basically the 2 PRIs are bonded together, and
> act as one.  During normal operation the calls come down each PRI in a load
> balanced fashion (IE if I've got 30 calls up, 15 will be on one PRI and 15 on
> the other).

The term you are looking for is NFAS (Non-Facilities Associated 
Signaling), and it's fully supported in Asterisk. You can configure your 
two PRIs as a single trunk group with a primary and backup D-channel, 
and calls can be handled on both PRIs equally.