The pinephone only has a wifi radio and lacks any cell radios, thus it is incapable of connecting to cellular networks. It's basically an 'internet tablet' and not a phone (at least in the 'traditional' sense) like the name suggests.
we also settled on the number, and the implementation of, privacy switches on the phone – there will be 4 switches in total: for the i) BT/Wifi module, ii) the modem, iii) cameras (front/back) and iv) lastly for the microphone.
https://www.quectel.com/product/eg25g.htm
Key Benefits
● LTE Cat 4 module optimized for M2M and IoT applications
● Worldwide LTE, UMTS/HSPA+ and GSM/GPRS/EDGE coverage
● Multi-constellation GNSS receiver available for applications requiring fast and accurate fixes in any environment
● Feature refinements: supports DFOTA*, eCall and DTMF*
● MIMO technology meets demands for data rate and link reliability in modem wireless communication systems