The oldest prefix is actually 010.

Last time used even before ADAM, Mutiara Telecom(DiGi), Timecell during ATUR450 time when people carry big water tumbler brick phones known as 大哥大(Tai kor tai).

Also this prefix is not only available in Malaysia as premium South Korean mobile numbers also share this prefix.
It is also their oldest mobile prefix which is shared by all their mobile celcos.

https://en.wikipedia.org/wiki/Telephone_num..._in_South_Korea

Normally if you watch KDramas, you'll noticed that their mobile calls that come in on their phones use 010 prefix.