SINGAPORE SMS: Products and Compliance – 8x8 CPaaS Help Center

Dialing code	65
Major Carriers	SingTel, M1, StarHub, TPG Telecom
Number portability	Yes
Message length	160 characters.
Support for Concatenated message	Yes
Sender ID Supported	Alpha, Alphanumeric, Long Code, Short Code
Sender ID Registration	Required (Long Code and Short Code)
Registration Time	2 Weeks (Both Short Code and Long Code)
Support for Two Way SMS	Yes
Extra Information	Unicode is supported Short code Sender ID is changed with a space being added between the last two numbers of Short code, e.g. "35694" becomes "3569 4".

Compliance
Prohibited Content:

The following types of messaging on all SMS messaging products are all prohibited:
- Advertising or promoting money-lending services

Regulations

With effect from 2 January 2014, Organisations must check with the Do Not Call (DNC) Registry to ensure that the Singapore telephone numbers that they are sending telemarketing messages to are not listed in the Registry - https://www.dnc.gov.sg/index.html
Under the advertising rules, which took effect on 1 November 2011, licensed moneylenders are not permitted to advertise their services via SMS - https://rom.mlaw.gov.sg/files/Advertising-&-Marketing-Directions.pdf

Industry Reference:
Advisory Guidelines on the Do Not Call Provisions (PDPC)