Numbers are categorised based on the first digit, thus providing ten possible categories, of which six are currently in use and the remaining four reserved for future usage.

Full telecommunication liberalisation in April 2000 led to rapid growth in the market, resulting in increased demand in numbers.

[1][2] Until 1995, calls to Malaysia from Singapore were direct and similar to domestic phone calls, with only the area code for fixed line or Malaysian mobile phone code and number being required, hence 03 for Kuala Lumpur fixed line or 019 for Celcom mobile carrier were dialed instead of +60 3 and +60 19.

In 1995, owing to the divergence of the two countries' numbering plans, the Subscriber Trunk Dialling prefix 020 was adopted.

Following the liberalization of the telecommunications industry, new carriers are assigned new carrier-specific codes for international and regional trunk call services.

3xxx xxxx - Business and Corporate IP Telephony Services or VOIP line numbers.

They also share the telephone exchanges with OpenNet locations, cable TV and '6'-regoed phone lines (each from SingTel and StarHub).