There is possible to activate AT+CLCC and on every changes states of modem , the modem send imself +CLCC… on receive or send call. Not to be make a pooling of AT+CLCC each ms
May I ask which HL module you are using?
Have you tried to enable the call state change notification? e.g. AT*PSCSCN=1
Please refer to AT command interface guide for HL to get more info, e.g.
OK very good, I work with Hilo NC V2 because this module is compatible with GSMR, i try to developp a GSM phone .
I usualy develop GSM PTE for raillway emergency call.