Asterisk + Cisco SPA510G

I have done a dumb thing as I learn Asterisk. I have been running Asterisk 1.8 for over a year and on the console performed a yum upgrade which I was not paying attention and now I am running Asterisk 10.12.

During the upgrade, and hundreds of hours of searching to solve my only issue with my current setup I come to see if anyone has an suggestions I can try.

Problem: Cisco 501G and 504G Phones will not transfer either Blind or Attendant while in a call. When a call comes in if any cisco phones tries to transfer, the caller gets put on hold, the attendant speaks the parking lot number and the user of the cisco phone hears the MOH. The user of the cisco phone is the only one that can pick up that call. When someone else tries to pick up the call they get Invalid Parking Lot Message.

At first I thought it might be a dial plan issue on the phone, then I thought it might have something to do with DTMF and have tried everything that I know or found online to solve the issue. My last resort is to research the backup process and restore process and start over. But really do not want to do that if I can avoid it.

Anyone have ideas or search terms that I am not aware of to try and solve this. I have been documenting a lot over the year and willing to learn more just not sure where to look.

Did you try any other brand of phones? Because “the smarts” in doing the Call Transfer is usually in the VoIP phone itself …