CAMEL Phase I - No access to SRF,NO online charging for SMS in HOME network and in Roaming.
CAMEL Phase II- Voice online charging, Access to SRF, SMS - Offline charging while roaming and no support of analyzed Information in BCSM
CAMEL Phase III- Voice online charging, SMS, Packet - Online charging while roaming and support of analyzed Information in BCSM
Note:
BCSM: Basic Call State Model