The Panasonic KX-TPA50 can be paired with the either the Panasonic KX-TGP500 or Panasonic KX-TGP550 to allow for up to 6 DECT handsets with each base unit. The Panasonic KX-TPA50 responds to the needs of SIP IP-Centrix/ Hosted PBX systems & Asterisk users. Conveniently designed so there is no need to set up a system telephone at every base. This system also enables you to use a range of convenient services provided by the carrier such as Call Forward, Voice Mail etc. Also, this system can be used as a wireless terminal. Features 2.1" Large LCD with white backlight on cordless handset Bright message waiting indicator Soft keys 100 phone book memory Integrated full duplex speakerphone 10 Last dialed number Local or network intercom DID specific ring tones 10 days st&-by & 5 hours talk time