The default phone call icon next to a phone number field does not work as expected on a conversation records.

If the customer details are being retrieved and shown on a voice conversation record, the call icon next to the phone number field does not start a call via Microsoft Omnichannel. Instead it tries to start a call with the default phone system being set on your pc and here you cannot choose Microsoft Omnichannel.

When using the exact same call icon not directly from a conversation record from the account record it start an omnichannel call as expected. The difference in this behavior is not logical. Whenever using the call icon or clicking a phone number in Microsoft Omnichannel it should always start a call in Omnichannel.

This behavior has been logged via MS Support and has been indicated as "By design".