This How-To covers setting up a conference on an Avaya B149 Analog Conference Handset. These handsets are supported from R7.0.
I have personally tested these steps on R9.0 and R9.1, but they should apply to any release the handsets are supported on.
Check there is a *47 Short Code in the IP Office configuration with the Feature set to Conference Add. If *47 is being used by something else other than Conference Add, create a new Short Code and use this new Short Code in the below steps.
Step 1, create the short code for the phone.
Step 2, set up conference
Press the Conference button on the handset and select Instant.
Step 2, Dial the first participant for the conference. When they have answered, press the OK button on the handset to confirm that they will be joining the conference.
Step 3, Adding The Second Party
After you have confirmed the first participant has joined, you will then be asked whether you want to add another participant. Press OK and dial the next number. When they have answered, press the OK button to confirm that they will be joining the conference.
Step 4, Complete The Conference
Once the second participant has joined, this should start the conference thanks to the *47 option added at the start. You can then either press OK to add other participants to the conference, or press the C button to stop adding participants.