Can I use your system to extend my cell phone coverage?

It does not extend cellular coverage, but it will extend the coverage of any smartphone that can use WiFi calling. Check to see if your phone and carrier support WiFi calling; most new phones on most carriers do. If your phone does not support WiFi calling, it might be a good time to look at a new phone.

Wilson Electronics makes very good cellular amplifiers/repeaters if you only want to extend the cellular network.