Brief TT-696 GSM Payphone is an outdoor Coin payphone.It bulids-in GSM 900MHz and GSM 1800MHz dual frequency module and be able to promptly offer payphone service during area with GSM 900MHz and GSM 1800MHz network. No matter in remote district or somewhere without telephone infrastructure,TT-696 GSM payphone is a best choice to offer phone service via GSM network. Feature Using GSM high quality dual band module to support GSM 900/1800 MHz dual band service Reliable operation from microprocessor control With flash memory system can be easily upgraded Automatic resend of PIN number for SIM card authentication on power reset. Usable coins : --Diameter: 18~32 mm --Thickness 1.2~3.0mm Coin Slot: -- Storage Capacity:7 coins -- Single slot for multi-coin,Max.7 coins to be inserted at one time --Distinguish 8 kinds of coins at maximum. Smart Refund: --Cashbox --Self-locking,Auto Reset --Capacity: 2.2 liters Allowing upgrade to Coin and Card Combi payphone. (Model: TT-886)