Avoid sites that promote IMEI changing or SIM cloning. Stick to read-only diagnostics.
As Jace turned to leave, Leo held up a finger. "Last one. If the signal is so thin you can barely breathe, don't try to call. Voice requires a constant, stable stream. A text is a single 'packet' of data. It’ll sit in the queue and wait for a half-second window of signal to jump through. It’s the ghost that gets out when nothing else can." get gsm tips
GSM (Global System for Mobile communications) is a 2G standard used for voice and basic data. Key areas for improvement/tips: coverage, capacity, handover, security, power, SIM management, and troubleshooting. Avoid sites that promote IMEI changing or SIM cloning