How to make a menu for conferences in Asterisk?

Question

Asterisk

Comrades!
Point in the right direction, where to dig.
Now there is a banal conference on Asterisk:
Contents of confbrigdge.conf

[confer]
type=bridge
max_members=20
mixing_interval=10
video_mode=none
record_file=/tmp
internal_sample_rate=auto

Contents of extensions.conf

[local]
exten => 900,1,Answer()
exten => 900,n,ConfBridge(1,confer)
exten => _XXX,1,Dial(SIP/${EXTEN},60,tT)
exten => _XXX,n,Hangup()

Simple but works. When you need everyone calls 900 and communicates, When you need to call someone from outside or he calls or we and then just transfer to 900 - everything is fine.
Question:
How can I make it so that when they call an external number, they get to the menu, where they were asked to dial the number of the room where they want to go, and when dialing they would be placed there?
As I understand it, confbridge does not have such functionality (in terms of records, etc.). Will I just need to make an IVR menu and write down the necessary notification text myself, and then just create a separate conference for each number with a config similar to the one above?

Answer 1

The config can be the same for all conferences, the rest is correct. Ask the caller to dial the conference number and call ConfBridge with that number as the first parameter. If necessary, first check the conference number for correctness,