Disable "recall" transfers

[jolouis]

This sounds like the PBX handing the call back to the caller rather than something the phone itself is doing. Not sure what PBX you're using so can't say for sure, but typically a "Recall" is when you Park a call and after a given amount of time nobody else picks it up. It gets sent back to you as a courtesy so the caller doesn't get lost in space forever, and you have the chance to try sending them to somebody else or doing a page/etc.

Even if it is happening due to direct transfers I would still expect it to be the PBX determining how to handle things, so check that side for your answer.