Distinct Ring on Internal Transfer or Call

I have a few GXP-2000 phones which support custom ringtones. I would like to have calls that are forwarded to another extension, or when an internal extension calls an internal extension to ring differently.

I am pretty sure something needs to be done in the dialplan regarding Alert Info, but I am not sure what and where in FreePBX I make the setting.

Can anyone help me out with this?

Thanks very much,