... imei change 3,support sending SMS & USSD 1/4/8/16 ports gsm voip gateway,wireless voip gateway ... GoIP-16)Model of GSM VoIP GatewayWe have 1, 4, 8, 16 ports GSM VoIP Gateway. there are ... 1SIM card, built-in antenna)GoIP-4( supporting 4 SIM cards ), GoIP-4i ( supporting 4 SIM cards, built-in antenna)GoIP ... anytime,the satisfaction of our customers is our greatest desire.9,What is our main express shipment? ...