The Retell 540 digital answering machine is compatible with an analogue telephone line or analogue extension on a telephone system.
An analogue telephone line is the same as a standard BT telephone line that you would commonly find in the home and the office. A broadband line is similar to an analogue telephone line, but you need an ADSL microfilter. If the telephone line is a digital line, such as an ISDN line, then the telephone will not work.
An analogue extension on a telephone system is one that allows an ordinary analogue telephone to work. Most telephone systems have a combination of extensions that either need certain types of system phones, or any ordinary analogue phones.
Please contact our customer service team if you require any further help or advice.