Teltonika products by design is for data connectivity and for a current moment he only voice-related use case they support is VoIP passthrough, meaning you can connect a dedicated VoIP device (such as an IP phone or ATA adapter) to the router, and it will carry the VoIP traffic over the cellular data connection.
The router itself, however, plays no active role in handling the voice services.
If native cellular voice is a requirement for your use case, we would recommend pairing a Teltonika router with a dedicated VoIP gateway or ATA adapter to handle the voice side of things.
We hope this clears things up! If you have any further questions, please don’t hesitate to ask we’re happy to help