Function: Connects a traditional analog phone line (POTS) to an IP-based phone system (VoIP PBX).
Use Case: Used when integrating analog phone lines into modern VoIP infrastructure.
Technology: Converts analog signals into VoIP and vice versa.
Example Application: A small business transitioning from traditional landlines to VoIP while still retaining existing PSTN lines for redundancy or local calls.

For more https://dinstarindia.in/GSM-3G-LTE-gateway/1-2-ports/