To transfer, flash, wait for the Intercom dial tone, then dial the extension you want to transfer to. Dial * and the extension number if you want to voice announce the call. Hang up to complete the transfer. The call will ring at the other extension, and return to you if not answered or covered to voice mail.
To hold a call, park it by transfering it to your self. Flash and dial your own extension number. To retreive the call, dial 6 and your own extension number.
You can also park a call and have someone else retreive it with Intercom 6 and your extension number, which is helpful if you don't want to directly transfer it to someone else. Flash, dial your own extension number. Hang up a moment, pick up again and do an all page, announcing for the party to dial Intercom 6XX for the call.