MTNL Mumbai gives its users another reason to rejoice. With the biggest festival coming up, MTNL users will be able to send and receive unlimited free MMSes. This offer is applicable to all its prepaid as well as postpaid users and will last till October 31, 2008. To activate GPRS/MMS service, a user can dial 1503 or send a SMS by typing ACT GPRS to 444 (prepaid) or GPRS4 to 555 (postpaid).