Some mobile phones can do Wi-Fi tethering but most just can’t do it.
Sim card maker Sagem Orga and Telefonica a Spanish mobile operator will be offering “SIMFi”, the first SIM card with integrated Wi-Fi targeted for mobile broadband services.
The embedded WLAN modem built into the SIM card can be controlled by the SIM toolkit applets running in the SIM, will turn the new generation USIM SIMFFi SIM card into a mobile hotspot/router that any device can connect to.
SIMFi is compatible with most existing phones.
Another ways of creating a mobile WiFi hotspot is using a Wi-Fi Router app on a WIFi enabled phone which is currently limited to a certain brand and OS.