Add GSM Command to Update Mobile Number in Existing Firmware (ATmega1284P + SIM800C)

We have a device that uses an ATmega1284P microcontroller along with a SIM800C GSM module.
In the current firmware, the mobile number is used for sending data.
We need to add a more GSM-based command functionality so that the operator can change/update the mobile number directly from the GSM module (via SMS), without modifying the firmware each time.

Scope of Work

The freelancer must:

Analyze the existing code (CodeVisionAVR environment) and identify where the number is currently stored.

Implement an SMS command feature using the SIM800C AT commands.

When the user sends a specific SMS, the system should:

Read the SMS

Validate the number

Save it to EEPROM

Use the updated number automatically for further SMS

Ensure the logic works even after powering OFF/ON.

Provide testing support to verify:

SMS command reception

Number update

EEPROM saving

GSM communication stability

Technical Details

Microcontroller: ATmega1284P

Platform: CodeVisionAVR

GSM Module: SIM800C

Communication: UART

Deliverables

Updated working firmware with the new GSM command functionality

Documentation on:

SMS command format

EEPROM flow

Code changes made