Due to the small physical size of Singapore , there are no area or trunk codes, with the Public Switched Telephone Network , Radio Network and IP Telephony all belonging to one numbering area, and thus comes in the same 8-digit numbering format. 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.

Similarly, until 1995, calls to Malaysia from Singapore were direct, with only the area code and number being required, hence 03 for Kuala Lumpur instead of +60 3, but in that year the Subscriber Trunk Dialling prefix 020 was adopted, owing to the divergence of the two countries' numbering plans.

Numbering have been changed since the liberalization of the telecommunications industry, with new carriers requiring different dialling arrangements system for calls to Malaysia, which require the use of the +60 country code, for example, to call Malaysia using M1 , a subscriber would dial 02160 , while making the same call using StarHub , the subscriber would dial 01860 .

Other international access codes in the 00x range will select various providers. Access codes in the 0xx range (e.g. 018 - StarHub's VoIP services or 019 - SingTel's VoIP services) will indicate a Tier 1 VoIP provider. Access codes like 1xxx (e.g. 1511) are indicative of a Tier 2 VoIP provider.