Lo que me deja pensando...
The power supply range of SIM800L is from 3.4V to 4.4V. Recommended voltage is 4.0V. The transmiting burst will cause voltage drop and the power supply must be abble to provide sufficinet current up to 2A.
Ensure that the input voltage nerver drops below 3.0V even when current consumption rises to 2A en the transmit burst. If the power volgate drops below 3.0V, the moduble may be shut down automatically.
+COPS: (3,"vodafone","voda ES","21401"),(3,"MOVISTAR","MSTAR","21407"),,(0-4),(0-2) OK