Second call drop the first


We are using Elastix 2.4.0-1 with asterisk and freepbx
We are using also openvox g400p with 4 gsm simcards.
And using Xlite or Ekiga Softphone.

What we want to setup, a number who customers will call, and the queue will dispatch the calls to users. If no one is free, the call stay in wait.

Our problem, is when an extension or user (ex:601) (is in call (inbound call), a second one call the same number, the first one receive it, and the big problem is that the second one if he drop his call, he drop also the first one.

We made in queue (skip busy agents, …)
It’s seem like, queue don’t detect that the first user is in call.

Sorry for my bad english, but can u please help us?

Do you allow call waiting on the extension/user?

No “call waiting” is disables.
Should we enable it?