Setting up and using the DTMF keypad on Telegram calls

To open the DTMF keypad during a call, swipe the screen up or left, or press the Back button. Keypad is sent to chat with user @siptg (in Softphone mode) or to chat with gateway account where call history is contained (in Gateway mode).

When configuring SIP-accounts from some service providers or registration from PBX, whose settings are not in our list of Server Templates, you may need to manually specify one of three methods of DTMF keyboard operation: RFC2833, inband and INFO (all methods, except inband, send confirmation).
DTMF keypad for voice menu calls in Telegram PBX

DTMF keypad operating methods

RFC2833 is the primary method of transmitting push-button signals in SIP networks. However, because of the freedom in implementation, some systems are incompatible with each other (in this case there are INFO and inband methods).

Inband is when the tone signal of the button press is transmitted in a common stream with the voice, but because of the audio codecs used it can be distorted and the receiving side does not recognize it. Therefore this method is usually used only as a last resort.

INFO is one of the newest means of DTMF transmission. On the one hand, the method is quite reliable and easier to implement than RFC2833, but not all operators support it due to its novelty.

The required value is specified without spaces, case insignificant.

See also

Payment options for the SIP.TG gateway for transferring calls between Telegram and SIP telephony

Frequent problems and solutions when setting up a gateway for calls between Telegram and SIP telephony

Configuring codecs for SIP accounts when setting up a SIP.TG gateway for Telegram voice calls

Setting up number conversion rules for SIP accounts

Error codes and their decoding that may occur when setting up a gateway for Telegram calls

How to transfer fare administration to another user, transfer of fare administration, and transfer of ownership of tariff

SIP.TG account management request to help users whose user categories can access the function

IP telephony operators for different geographical areas, vetted by our team

Purpose, benefits, installation and configuration of own Worker servers for SIP.TG

Purpose, benefits, installation and configuration of your own Telegram Session Store for SIP.TG