Most of the the scam callers from overseas dont care to spoof since it is an extra cost & law enforcement hear can't reach them. Why bother spend money for spoofing?
Also, the fake IRS, & Fake Microsoft Suppot worka foe thwm because they gain your confidence so thier "con" works with many people. The message they leave and the fact that you can call them back gives the perception that they may be legitimate.
Note: The FTC has a team that investigates the mumbers/reports they receive and they work with the phone carries to shut these numbers down. The phone carriers are also taking these reports seriously.
Don't just ignore these callers . Report the the number. Btw the carriers can see the call history of the number you are reporting .
This is not the same for US or Canadian scammers. They spoof because they face fines and jail time if they were to threaten, steal, harrass, etc.
If, as you say you are an engineer, I wouldn't let near a project I was working on. Your writing skills, border on illiteracy. Where did you get your degree?
Maybe you should proofread your post before presenting it and looking like a fool. And spoofing a number is not an extra cost as the equipment and ability is there already. I think he got his sheepskin at the farm after dropping out of Whats-a-Matta-U.