This to me seems to be a complete misunderstanding of the telcos business and motivations. They sell mobile telephony - voice, sms, and data - and their _prime objective_ is to make it as easy as possible for their customer to spend as much money doing that as possible. Making you wait five days to get reconnected to "your number" when you have, for whatever reason, lost control of it is just not going to happen. They'll move mountains to get you back onto your data/voice plan before you've walked out of the store.
Nobody ever advertised their phone/sms plans as "banking grade secure". Telcos have been telling us for years that they are explicitly _not_ secure for that:
https://www.itnews.com.au/news/telcos-declare-sms-unsafe-for...
Communications Alliance chief executive John Stanton, representing the interests of mobile providers Telstra, Optus and Vodafone, took the extraordinary step of of declaring the technology insecure in the wake of numerous reports of Australians being defrauded via a phone porting scam first uncovered in Secure Computing magazine.
"SMS is not designed to be a secure communications channel and should not be used by banks for electronic funds transfer authentication," Stanton told iTnews this week.
Telcos are not interested in securing that, they get _way_ more complaints from people who lost/broke their phone who want their replacement one to work RIGHT NOW, than they do from people who got defrauded with a sim porting attack. And the first group of people are spending _way_ more money collectively than the second, so of course telcos will continue to make it quick and easy to sim port.
Everybody else needs to deal with that. While sms 2FA is marginally better than not having any 2FA at all, it's not the telco's problem if you choose to use it to "secure" your $100k worth of crypto. In my mind, a large part of the blame here goes to COinbase for even offering it. I'm also looking at your PayPal...