[Users] Multi Call-Legs accounting configuration

[Ricardo Carvalho]

I want to use Multi Call-Legs accounting to properly account forwarded 
calls made "in the phones". For example user A calls user B which 
forwards the call to user C. There is only one SIP call but with 2 legs 
( A to B and B to C). Accounting the legs of a call is required for 
proper billing of the calls.

As can be seen in acc module documentation, I've added the following 3 
lines to my openser.cfg script:

modparam("acc", "multi_leg_enabled", 1)
modparam("acc", "src_leg_avp_id", 110)
modparam("acc", "dst_leg_avp_id", 110)

Although, after testing some forwarded calls, nothing has been written 
to src_leg or dst_leg columns of acc table!!
What have I done wrong? How may I implement this feature correctly?

Regards,
Ricardo.