Add conference room to ring group?

I know we can add extensions to ring groups, but wanted to know if it is possible to add a conference room to this ?

Only if there’s a phone in the conference room.

I don’t think I understand the question.

Try adding a # at the end of the conference number in your ring group.

@cynjut : I meant the conference room created inside asterisk.
For example, I have a system with extension 10,20,30 and conference room 200.
When a user calls, I would like extension 10 and 20 to ring, but also connect to conference room 200.
But, I would have a PIN code for that room… so if the caller knows the PIN he can log into the room.

Is it more clear ?

thanks @dicko ! It works !