asterisk PBX Configuration

We are looking for Click to conference Solutions..

I need support for "Click to conference Solutions" we would like to Dinstar GSM Voip Gatway.

Step 1

I will call API then it should make a conference call.
Eg: https://astersik-ip/api-key.php?caller1=991234567&caller2=998989898&caller3=9849098490&caller4=984898484&caller5=989999999
all callers should connect to conference call.

Step 2
Should get announcement in the call
eg: caller1 connected, caller 2 connected, caller 3 connected ..... ....

Step 3
When people on the conference call, if we need to add another person.
We should be able to add by tying *333 on the Dialpad DTMF keys.
in the database we will pre-defined varibles.
333 --> 9848424242
444 --> 9858585858

Step 4
Call Recording.