SIM808 has GSM, GPRS, GPS and bluetooth.
In this video, SIM808 is interfaced with NodeMCU. Initially only GSM is accessed through NodeMCU and Later on GPS. At last, geographical location is identified, a Google map URL is constructed in which latitude and longitude is embedded. So that, geographical location of device can be observed on Google map.
Code for only GSM: https://drive.google.com/file/d/1MefvpWqMjEcmyCB1TRJeccl0xrzBTcVd/view?usp=sharing
Code for only GPS: https://drive.google.com/file/d/10IKNBFoY03nIbgD9tE0rfBF1osaQYKFg/view?usp=sharing
Code for GSM and GPS: https://drive.google.com/file/d/12u37k8rUtDiX9xec44iq4TRhoerVBCV6/view?usp=sharing
source by Mahesh Pawaskar