problem sim800h sim800l

Hello, i have a problem for few month... very crazy : my sim800 seems looping infinitly when module communicate with operator. Why ?? please help me :confused:

(with arduino 9600bps)

== logs ==

RDY +CFUN: 1 +CPIN: READY Call Ready

RDY +CFUN: 1 +CPIN: READY AT+CBC +CBC: 0,33,3668 OK

Call Ready RDY +CFUN: 1 +CPIN: READY Call Ready

RDY +CFUN: 1 +CPIN: READY ATD+336xxxxxxxx; OK Call Ready

RDY +CFUN: 1 +CPIN: READY Call Ready

RDY +CFUN: 1 +CPIN: READY Call Ready ....