When sourcing a GSM Pump Controller, you must prioritize network compatibility, ensuring the device supports 4G LTE or 5G bands as 2G/3G networks are being phased out globally. Look for controllers with high-gain external antennas to ensure stable signals in remote areas. Key functional specs include Phase Failure Protection, Dry Run Protection to prevent motor burnout, and Voltage Fluctuation Monitoring. For high-power pumps, ensure the relay contact capacity matches your motor's starter requirements (typically 30A to 40A for direct control or compatibility with external magnetic contactors).