You can administer an alternate routing destination number either as a subscriber individual alternate routing destination number for one subscriber or a source group related alternate routing destination number for a whole source group of the related subscribers.

In order not to waste memory, for some OOS scenarios, it might be enough, You would confine to source group related alternate routing destination numbers.

As You can administer a source group related alternate routing destination number either as a complete number (EXTNO = 0) or as a incomplete number (EXTNO > 0), You also have the possibility to reach subscriber individual destinations with the supplementation. request (EXTNO > 0).

A supplementation will be done at time of alternate routing execution by call processing with the administered length (EXTNO) of the called subscribers extension number.

If You administer both kinds, and the numbers are different, the subscriber individual alternate routing destination numbers will be used with higher priority than the source group related alternate routing destination numbers. With this design, You can treat special subscribers (vips) different than the rest of subscribers of a source group.

In case of usage, the alternate routing destination number will be checked for being usable to reach an alternate destination successfully. If it is not possible, to reach an alternate destination with the subscriber individual alternate number, another attempt will be done with the source group related alternate routing destination number.

Depending of the OOS scenario (1 --> 4) the alternate routing destination numbers will be checked for usage in following hierarchical manner: