Enable 3G on smartphone and for Wi-Fi create the GS module Limited AP mode with following DHCP settings. The smartphone then uses 3G for reaching to internet as DNS server and gateway is not exposed in DHCP Offer by GS/Wi-Fi.
AT command format is as shown below.
For example in below case, iPhone6 was able to reach internet and ping the GainSpan AP as well:
iPhone 6 (3G enabled) - Associated to GS WiFi.
at+wm=2 //Mode as Limited AP
at+nset=192.168.2.1,255.255.255.0,192.168.2.1 //Set IP Address and subnet mask and gateway
at+dhcpsrvr=1,1,1, //Start DHCP server but do NOT provide gateway or DNS server in DHCP
at+wa=test3G,,3 //Start limited AP
Enable 3G in Iphone6
Enable WiFi in iPhone6
Connect to test3G WiGi
Test ping to GainSpan IP: Working
Test ping to google.com: working
Browse google: working.
Note: iNet Tools application is used for PING test. Standard browser is used for browsing Google.