“0” - hash over callid

“1” - hash over from URI.

“2” - hash over to URI.

“3” - hash over request-URI.

“4” - round-robin (next destination).

“5” - hash over authorization-username (Proxy-Authorization or "normal" authorization). If no username is found, round robin is used.

“6” - random (using rand()).

“7” - hash over the content of PVs string. Note: This works only when the parameter hash_pvar is set.

“8” - use first destination (good for failover).

“9” - use weight based load distribution. You have to set the attribute 'weight' per each address in destination set.

“10” - use call load distribution. You have to set the attribute 'duid' (as an unique string id) per each address in destination set. Also, you must set parameters 'dstid_avp' and 'ds_hash_size'.

The algorithm can be used even with stateless proxy mode, there is no SIP dialog tracking depending on other modules, just an internal lightweight call tracking by Call-Id, thus is fast and suitable even for embedded systems.

The first destination selected by this algorithm is the one that has the least number of calls associated. The rest of the destination list is taken in order of the entries in set - anyhow, until a re-route to next destination happens, the load on each address can change.

This algorithm can be used only for dispatching INVITE requests as it is the only SIP method creating a SIP call.

“X” - if the algorithm is not implemented, the first entry in set is chosen.