With NI-2 Does asterisk support D-channel sharing?


#1

Hi,

Some carrier(like QWEST) support D-channel sharing between several PRIs. Here is the paragraph from Qwest web site:

"With the NI-2 protocol, you have more flexibility when purchasing multiple ISDN PRI. The first ISDN PRI must be configured as a 23B+D. The additional ISDN PRI may be configured as 23B+Back-up D or 24B. One D channel can do the signaling for up to 479 B channels (20 facilities) if they all terminate at the same destination. "

Does asterisk libpri support this feature?

Any info will be appreciated. Thanks!


#2

this feature is called NFAS (non-facility associated signaling) among telecom folks.

An example way to set it up with a DS-3: 4 NFAS groups of 7 T1s each, with a primary and backup D-channel in each group of 7 T1s. For the added complexity (and potentially loss of features with the telco), you get an extra 5*4 = 20 B channels on top of the 644 B channels you’d get if you had a D channel on every T1 of the DS-3.