In the busy world we have to do more calls in high networks for this it is used as SIMADO GFX44 is a fixed configuration GSM3G-FXS voice gateway. It connects with the existing telephony devices via FXS interface. Up to 4 SIM cards can be placed inside the SIMADO GFX44 gateway allowing up to 4 concurrent calls. The calls to mobile numbers are placed via the GSM3G SIM cards, reducing higher fixed-to-mobile interconnection charges.