Registration time

Hello. thank you in advance for your hard work helping desperate people like me. I have two SIM cards from from different companies , both were registering and sending GPRS data correctly. One of them stop registering, however when installed in a cell phone works fine. I checked how long the the SIM800L is trying to register and it is about 25 seconds from power on. Has it tried to connect to all netwoks available?.
Is it possible to increase this time?

It must have tried by that time. A reboot of the module restarts the registration process. May be your network is not accepting the connection due to too many reboots or blacklisted IMEI numbers.