Transfer Calls between ATA Ext and Deskphone

Hello,

I am trying to figure out how I can transfer calls from an Analog Extension (provided by a Grandstream HT802) to a regular desk phone (such as a gxp1608) when both are connected to FusionPBX. I have been through the settings on the HT802 to see if there is any functionality that I can do with the flash key on the analog phone, but I'm not having any luck getting this to work.

Any help would be greatly appreciated.

Thanks!
 
*1<extension> should transfer a call, last I tested it that worked for transferring calls to any extension inside a domain from a HT802.

We have labels that list extensions and feature codes for users on analog ATAs & cordless Grandstream DP720 phones, I'd get complaints if *1 didn't work :p