3 Way Call / Conference Call fails

Hi All,

We are running FreePBX version 2.11, Asterisk 1.8.11, and having problems with one of our IP phones trying to make a 3 way call. The phone is a Grandstream GXP 2100 with the latest firmware and conference calling enabled on the endpoint.

When we try to make a 3 way call we call the first number and get them on the line, place the caller on hold and dial the 2nd number. Once the 2nd number is connected we hit the conference button and then choose on the phone to join the conference with the 1st line. The phone indicates “Conferencing Failed”.

Upon trying this from connecting to another FreePBX server / same versions and the same procedure as followed above the 3 way call works fine and is immediately conferenced.

It appears to be a configuration issue somewhere on the FreePBX server but I cannot seem to find where that is (I would think somewhere on the extension settings itself). Also note on the same failing server when we try this from another IP phone (SNOM 370) the 3 way calling seems to work.

Appreciate any help you can give me.

Best Regards,

It is the phone not the server.

The phone works fine on another duplicate server with the same version of FreePBX and Asterisk.