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
....