This article explains which settings you need to configure to answer calls in the Bitrix24 mobile app.
You can use this option if you connect your PBX with the SIP connector.
Learn more: What is SIP connector?
If you use an app installed from the Bitrix24 Market, you cannot receive calls in the mobile app. Remove the app and connect your cloud or office PBX with the SIP connector instead.
Learn more: Connect cloud hosted PBX
If you use a rented Bitrix24 phone number, you do not need to configure any additional settings to answer calls in the mobile app.
Learn more: Rent a number in Bitrix24