Settings and use of the DTMF keyboard when Telegram- calls

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

When setting up SIP accounts from some telecom operators or registering with a PBX whose settings we do not have in the list of Server Templates, you may need to manually specify one of three methods for the DTMF keyboard: RFC2833, inband и INFO (all methods except inband send confirmations).
DTMF keypad for calls to Telegram for PBX voice menu

DTMF keyboard operating methods

RFC2833 - the main method of transmitting signals about pressed buttons in SIP networks. However, due to freedom in implementation, some systems turn out to be incompatible with each other (in this case there are INFO and inband methods).

inband - this is when a button press tone is transmitted in a common stream with voice, but due to 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 ways to transmit a DTMF signal. On the one hand, the method is quite reliable and easier to implement than RFC2833, but due to its novelty it is not supported by all operators.

The required value is indicated without spaces, the case of letters is not important.

See also

Payment methods 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 the SIP.TG gateway for voice calls in Telegram

Setting up number conversion rules for SIP accounts

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

Methods for transferring tariff management to another user, transferring the right to administer the tariff, as well as transferring ownership of the tariff

Request for SIP.TG account management to help users whose categories of users have access to the function

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

Purpose, advantages, procedure for installing and configuring your own Worker servers for SIP.TG

Purpose, advantages, procedure for installing and configuring your own Session Storage Telegram for SIP.TG