Thanks Awneil for your help. The options provided in the link:
Option 1. Design your hardware to pull the CTS line so the Wavecom processor things there is a serial cable connected.
Option 2: When the code is ready to apply the DOTA file, issue a “at+wrst” to be executed two minutes later. Issue the adl_install() command. The idea is that ff the adl_install does not reset the Wavecom modem, the the at+wrst will do so anyway two minutes later
Option 3: When the DOTA file is finished downloading, just set a non-volatile flag and reboot the WMP with a normal at+cfun=1 command. When it starts up it first checks the flag. If set, it disables all debug info and unsollicted responses to UART1. It then clears the flag and executes the adl_install() which works now because there is nothing on serial port.
Out of these Option 2 didnt workout for me. Does wrst actually work? Because the unit never resetted. Im going to try Option 3. Hope this would work out.