Groupcall with 2 PSTN numbers

Hello
Is it possible in Teams to have a conversation with 2 PSTN Numbers without having a meetininvite

The Usecase

1. No meeting

2. PSTN calls Teams Number

3. Teams User adds another PSTN number

4. 3 Users (2xPSTN, 1xTeams) talk to each other

If yes what are the conditions (policies)

Regards

JFM_12