At a high enough volume, links will also get you blocked by carriers

Yeah, we pass all of our twilio messages to our staff via a special Slack channel.

Which pricing tier do you use? I've been thinking of starting with the for a while. Now we use a hodgepodge of Skype and WhatsApp

For which, Slack or Twilio? We have a basic twilio account, paying $1/mo for the phone number, and $0.1/msg or whatever it is.

On Slack, we have a paid account at the standard level, we've had that for years.

One note, both Google and Apple detect that our number is Twilio, and won't let us use it for 2FA, sadly (our original use case).