Digital extensionthe siemens optipoint 500 standard system telephones are digital telephones that will fit to the siemens hicom or hipath system the extensions have to be set up to except one of the siemens optipoint 500 range telephone or they will not work if the opitpoint 500 telephone is plugged into an analogue extension or telephone line then it will not workoptipoint with fully duplex speakerphonethe siemens optipoint 500 standard system telephone has the same specification as the basi