Wireless GSM transceiver

Features:Based on GSM 900/1800MHz or 850/1900MHz.Support reverse polarityCan connect to PBX.with Li-battery, support standby time over 18hours.5. with 2RJ 11 phone port, can be connect with extension;Main Functions:1. Suitable for GSM 900/1800MHz or 850/1900MHz, using SIM card2. Making & answering calls after connecting to telephone set3. Available to connect with telephone set, Billing machine, etc4. Supports the functions of redialing and hands-free5. Voice adjustment of