My fixed phone got government office fax number giving calls at early morning and nights.

It's can't be govt offices after operating hours. 11pm - 3am?

When answered, no one on the other side but you hear like fax tones.
They are called phantom calls to detect active phone lines for future tele-marketing forwards.

This is obvious inside job either by TM contractors or civil servants.

Also TM VoIP call servers might be bugged or infected by malicious virus.

Anyone got receive Nigerian scam calls even originating from Bukit Aman number (03-26163999) before?



How they got the number, I suspect government offices and numbers are using UniFi VoIP accounts and they've all been leaked by inside jobs.
Most notably, are TM installers/contractors who provision the accounts or even the government IT staff who have access to the communications infrastructure.

If people can gain access into the UniFi BTU which holds the UniFi VoIP account settings/login, lots of unthinkabe things can be done with it.
One of it is running Nigerian scam call centres and future threats such as voice keyword detection now happening in western countries.

Forced bundling of voice service is actually unnecessary. We should follow SG and Thailand's national broadband initiatives. They don't force bundle voice and video on their services.