The GSM Wireless Desktop Telephone support 2 SIM card(Not included). Working Frequency: GSM900/1800MHz. Superior service quality Strong quality battery Features include High capacity phone book, SMS functionality, Call history, Caller ID,Loud speaker, Caller ID, redial handsfree function, Different ring tones and alarm ringers, Backlight LCD with date, time, signal strength and battery volume status icons Easy & Simple to Use Can be put on desk . Widely used in family house, office, hotel or telephone shops etc Backlight LCD with date, time, signal strength and battery volume status icons Easy & Simple to Use Can be put on desk . Widely used in family house, office, hotel or telephone shops