Enhance Firmware for ATmega1284P Device

We have a device built on an ATmega1284P microcontroller that communicates using a SIM800C GSM module.
Currently, the firmware has a hard-coded mobile number used for sending data/alerts.

We need to enhance the firmware so that the operator can update/change the mobile number remotely via SMS, without modifying or reflashing the firmware.

Required Modification

Add support for GSM-based SMS command(s) to:

Read the existing mobile number stored in EEPROM.

Update the mobile number using a predefined SMS command .

Validate the received number (length, digits only).

Store the updated number in EEPROM permanently.

Send back an acknowledgment SMS confirming the update.

Technical Details

MCU: ATmega1284P

GSM Module: SIM800C

Programming Environment: CodeVision AVR

EEPROM is available for storing updated mobile number.

Deliverables

Updated firmware source code (C CodeVision AVR)

HEX + EEP files ready for flashing

Short documentation explaining:

SMS command format

How to update/reset the stored number

Any changes made in the code

Expectations

Clean, well-commented code

No impact on existing functionalities

Quick turnaround preferred

Support during testing