Digital extensionthe siemens optipoint 500 basic telephone is a digital telephone that will only work on a digital extension on the siemens hipath or hicom system the extension has got to be set up for one of the optipoint 500 range as the telephone will not work on any other type of connectionoptipoint with adapter interfacethe siemens optipoint 500 basic system phone has all the same features as the optipoint entry telephone but is also has the adapter interface this allows the user to add