Digital extensionthe siemens optipoint 500 economy phone is a digital system telephone for the siemens hicom and hipath systems it does need the extension it is being plugged into to be compatible with the siemens optipoint 500 range as it will not work in any other type of extension or telephone lineoptipoint with lcd displaythe siemens optipoint 500 economy system telephone is the first phone in the range to have an lcd display this means that the user will see information such as the incom