I don't think you have an idea of how a telco works.
There isn't some giant firewall that every request goes through so you can say "block port 21" and your problem is fixed. Most of the equipment is talking directly to each other on many different private networks some of which may be managed by third parties. And as companies shift towards virtualised, container based architectures it can become harder as there is more complexity as companies transition.
And not sure if you've worked at a large company before but the idea that they have this army of highly skilled people who just make sure everything works perfectly isn't what happens.
Actually I have, most of my employers and clients the past few decades have 80k++ employees. I understand that there are PLENTY of interfaces on a company on the size of Vodafone (let's call them that) that have live access to networks, infrastructure, and what have you (e.g. Huawei, Nokia, Ericsson to name the big whales) and myriad other smaller ones monitoring, fixing, live, a million moving parts.
The responsibility and accountability remains though. I do not accept the 'we are big and busy so we drop the ball'.
There isn't some giant firewall that every request goes through so you can say "block port 21" and your problem is fixed. Most of the equipment is talking directly to each other on many different private networks some of which may be managed by third parties. And as companies shift towards virtualised, container based architectures it can become harder as there is more complexity as companies transition.
And not sure if you've worked at a large company before but the idea that they have this army of highly skilled people who just make sure everything works perfectly isn't what happens.