DESC: The Panasonic KX-TA824 system is designed to be a replacement/upgrade to the long-time solid performing KX-TA624 system. Out of the box the KX-TA824 comes with 3 telco lines and 8 extension ports. The KX-TA824 is also expandable up to 8 telco lines and 24 extensions. Buy the way, these extension ports can take either the KX-T7700 series propietary phones, OR single line telephones (Plain Ole' Telephones) and pass caller ID to them both! The KX-TA824 is the first Panasonic system to offer, an optional, plug-in message card (KX-TA824-92). Providing each phone with it's own mailbox to take messages from callers. A message waiting light will be left when a caller leaves a message on the KX-TA824.