1,GOIP_8 / gsm goip gateway for international calls 2 NAT transvesal 3,VLAN and QoS 4. ... 8 gsm voip gateway/gsm goip gateway 8(GOIP_8) free international calls Specification:1. 4 GSM channels,up to 8 sim ... without platform,what is more,it is free roaming for international call.you just pay the local callmodel1: model2:model3:model4 ... 8 gsm voip gateway/gsm goip gateway 8(GOIP_8) free international calls