The GSM Wireless Desktop Telephone support SIM card(Not included) with a working frequency  GSM 900/1800 MHZ. Easy to set up with no ground wire needed. Phone has a superior service quality with a strong Easy & Simple to Use: Can be put on desk or wall mounted. Widely used in family houses, offices, hotels or telephone shops etc.Features include High capacity phone book, SMS functionality, Call history, Caller ID,Loudspeaker, Caller IDit has very loud volThe GSM Wireless Desktop Telephone supports 2 SIM cards(Not included).Working Frequency: GSM900/1800MHz.Superior service qualityStrong quality batteryFeatures include High capacity phone book, SMS functionality, Call history, Caller ID,Loudspeaker, Caller ID, redial andhandsfree function, Different ringtones and alarm ringers,Backlight LCD with date, time, signal strength and battery volume status iconsEasy & Simple to UseCan be put on a desk or wall mounted.Widely used in family houses, offices, hotels or telephone shops etc.ume that will make it audible enough in such a way that no one can miss a call.