Port a contract MTN sim with a replace number

[Kiemo]

Hi guys I want to know if it’s possible to transfer the data and airtime to a different number if you still on contract

Like for example I have this contract MTN SIM card that I’m not using with a new number

So I want to transfer this to my Telkom number

I’ll stay with MTN because it’s a contract with them but I don’t want to use two sims I just want my Telkom number with MTN benefits lol

Help