Take two cases: since the tsunami, Sri Lanka's largest telephone company has started an early-warning system which would send SMS messages to every mobile phone in an area at risk of flooding.
The system can successfully prevent form losing and thefting mobiletelephone.
该系统可以有效防止移动电话的丢失和被盗。
3
The cellular digital packet data (CDPD) is a system which borrows idle radio channels from the existing cellular mobiletelephone networks for packet data transmission.