[ypkuby]

> I travel quite a bit and change phone numbers often. Most of the time when I am traveling I am in locations that have poor or nonexistent cellular service.

Use Twilio or VOIP.ms, very cheap. You can do 2fa easily, just top up $20. I find that the biggest cost for me personally doing this is the $1/month phone number rental fee. I use maybe ~50c every month on 2fa. It's an already solved problem.

> I have debated using Twilio to create my own number pool of international numbers and a way to check my messages via a web portal instead of relying on messaging. Are there any current apps / services that already do this effectively?

VOIP.ms has a very nice SMS gateway, they will automatically relay SMS messages to your email address. You pay a bit of a premium for it (eg, of SMS cost 0.001c, you pay 0.0015c if I recall correctly) - but it's almost immediately delivered without issue.