A:Answer Hello. This phone has a built-in answering system for the landline, so the callers can leave messages. As the phone system was only tested with a landline connection, we encourage you to check directly with the telephone service provider for additional information. Please note that if you encounter issues with the sound or related to Caller ID services when using VoIP, the phone may require a DSL/ADSL filter to be installed on the line by your telephone service provider. -G