Sim conversion from Pre Paid to Post Paid number. New Delhi: The Department of Telecommunications (DoT) has come out with proposed new guidelines for Sim Card conversion. As per the new guidelines, users can convert from Pre Paid to Post Paid number through an OTP based process. Details on the guidelines are further awaited. If implemented, the process may be akin to the one that DoT had allowed few years back for upgradation of SIM upgradation to 3G or 4G from 2G. To upgrade the SIM card to SIM upgradation to 3G or 4G from 2G, the subscriber needs to generate a request through customer care or online or point of sale of the company. Once the request is received, the operator will issue a new SIM card to the subscriber.