Panasonic KX-TA824 Analog Phone System Product Features:

Will work on Voice over Internet Protocol (VoIP) lines such as Vonage

Can be used in conjunction with:
These telephones: KX-T7020, KX-T7030, KX-T7031,KX-T7040, KX-T7050, KX-T7720, KX-T7730, KX-T7731, KX-T7735, KX-T7736, KX-T7740, KX-T7750,
These cordless (wireless) telephones: KX-T7880, KX-T7885, KX-T7895, KX-TD7895, KX-TD7896