Light users will probably find that prepaid service is more economical. SIM card starter packs cost between RM10 and RM30, depending on current promotions. Digi is the most popular with prepaid users, due to cheap SMS and call rates, especially for international calls.
Prepaid users are required to present identification (such as a passport) and complete a form when purchasing or activating their SIM card.
Calls within an operator's network are cheaper than calls between networks, so if two or more people are getting SIM cards, it makes sense to get them from the same company.
People who expect to make heavy use of their phones will save money by using a monthly postpaid plan. Also, postpaid is the only way to get unlimited GPRS data access (e.g., RM100/month from Digi). With prepaid, GPRS is always metered.
Non-Malaysians are required to make a sizable deposit (typically RM1300) when signing up for postpaid service. Some people get around this by asking a Malaysian friend or colleague to open the account on their behalf.