i have a customer i who just add 3 phones to an existing account to be used in a different location, to start the phones couldn't boot up using ftp, (however trying to telnet port 21 to FTP server worked) he plugged it in a different location to download the config files and it works fine now.

however when he is transferring a call attended only he gets a error on the screen transfer failed blind transfer work fine as well as conference works only till he holds the phone the minute he hangs up the conference terminates with no error message

Im not sure these 2 things are related but i thought it is worth to mention since it shows it is some thing local, any thoughts where to start ?

thanks in advance