To use the Gateway, you must have your own Telegram account for this purpose. SIP.TG does not register Telegram accounts for its users.
Gateway is a mode that allows you to connect your Telegram account to a phone PBX (office or cloud-based) to forward voice calls to and from Telegram.This means any call to your Telegram account is handled by the PBX, and for outbound calls from the PBX, the same Telegram account can be used as the “caller number”.
When it’s useful: if you have a sales or support team working via PBX and want to make and receive calls through a Telegram account (not a bot) — to stay closer to your audience in the messenger.