About conference call on HTC One M8 ???

[AC Question]

when i am trying to conference my cal it show .. unable to conference but why .. can you help me to give me information nd how could i worked out ...

 

[B. Diddy]

Welcome to Android Central! Is this how you're doing it? HTC One (M8) - Setting up a conference call - COMMUNICATION - How-tos - Support | HTC United States. Do you get an error message? What exactly does it say?