Multi-Line Phone

I am using two Grandstream GXP-2000 phones (a 4 line phone) with elastix. I have them each setup as their own extension. I have a ring group setup so that if a call comes in, it will ring both extensions. The phones are working fine except that if I am on a call and another call comes in, the call will only ring on the open extension (not the one I am using). How can I get the call to ring on the second, third, etc. line of my extension even if I am in a call? Thanks.

 

For anyone who might be interested, I have found the solution to this problem.

In FreePBX, you need to enable call waiting for each multi-line extension that you have. If you don't have the call waiting module installed, you will need to install it first.

The call waiting module works like normal call waiting on single line phone, and works as a multiple call appearance for multi-line phone.