[Freeswitch-users] how to pass the original caller number through FS gateway?

i have 2 FS server connected, FS A reg to FS B, and FS B is a gateway for FS A, the external conf of FS A is <gateway name="gwB"> <param name="username" value="1000"/> <param name="password" value="1234"/> <param name="realm" value="192.168.0.100"/> <param name="proxy" value="192.168.0.100"/> </gateway> and i can make call from a phone(e.g. 1001) regestring in FS A to one(e.g. 1005) in FS B, but the calling number shown on the called party is "1000", how can i pass the original caller number("1001") to the called party in FS B?