Alcatel Unleashed

Hello everyone
I'd like to know how to make two numbers ring at the same time and when one is picked up the other stops ringing.
I've thought of a group of extensions, but the problem is that you have to create a third number and it's this number that you have to dial, for example: call A and B rings at the same time
but with extension grouping, you'd have to call C, which would make A and B ring at the same time. I'd just like to make two extensions ring by calling the A number, which would make B ring, not C.

just a point, in set's group only the sets in the group will ring in parallel or in cyclic mode. The third number (C for your case) as you said in only the calling number and it's not a set physically said.
For your case
1-tandem
2-set supervision with ring
3-parallel set supervision with ring

Hello, it's nice of you to answer, can I have some detailed explanations on the procedure please?