Which OS is used in Spice, Maxx, Airfone, & other chinese type mobiles ?

Can anybody tell me which OS is used in Spice, Max, Airfone, Karbonn & other low cost mobiles. ? Is it possible to upgrade this OS or no ? Many of the phones support JAVA applications, so are there new JAVA applications available for this phones ? Can anybody throw light on this?

Thanks,
Niraj Posted in: #Coffee Room

Regarding Chinese phones, go through this page -> Chinese Models & Cloned Phones - GSM-Forum