After trying the chan_ss7 with Erricson switch, I've found that there is no Ring Back Tone, since ACM ISUP message should be sent before CPG ISUP message for Erricson. So It's a very dirty hack to send an ACM message to start receiving the ringback tone. Please see attached.

NOTE: This is a quick and ugly hack! It will be a good idea to fix it in a right way.

Possibly that hack will be usefull for Erricson ISUP dialect, since ANSI ISUP requires CPG before ACM

Asterisk ss7 channels

PATCH IS UPDATED! Just patch -p0 < rbt.patch.diff