Putting this out there because it was frustrating as hell trying to find more information online specifically for Celcom voicemail and how to do so when you’re already overseas.
Because I found out too late while overseas that voicemails are charged roaming rates… ugh.
IF YOU ARE ALREADY OVERSEAS:
- Call *123# this is FREE
- Once you call this number, an automated response will appear telling you to wait for Celcom to call you back shortly.
- You will receive a call from Celcom’s call center (019 6011111) almost immediately and the automated voice will ask you to wait for the customer service agent to pick up the call (this took about 1 minute for me).
- Once you speak to the agent, just inform them you want to deactivate voicemail and after some identity verification they will ask you to be on hold for a bit while they get it done (very fast).

If you’re in Malaysia, just call the customer service number 019 6011111 and select the option to speak to an agent. I listened through the menu options and I didn’t hear anything for voicemail so I think it’s best to just speak directly to the agent.
For other service providers, SoyaCincau’s article covers it here