Hi sir nokia e71 3g problem Sir i hv a problem while using nokia e71 when i connect

Sir i hv a problem while using nokia e71
when i connect with my wifi network i can make a video call by using fring software but when i connect with my airtel network i cant make a video call i can only make a fring call but not a video call but the same airtel sim when i insert in my nokia e51 i can make a video call
can u pls tell me the exact problem and send me the solution of this wether it is hardware problem or software problem
pls help me