Does anyone know if you need a licence to do SIP on IPECs?
Does it Support SIP Peering (NON AUTHENICATED SIP VIA MPLS IP AUTHENICATED BY SERVER.)

You do not need a license for SIP Trunking. You do need a license if you want to use a 3rd party SIP Phone.

If you're trying to tie two IPECS together, you're better off getting the TNET keycodes.

If you're just wanting to tie two different systems together via SIP, then yes it can be done, but you'll probably have quite of bit of time involved with trial and error.

thanks nfcphoneman. much appreciated.