I haven’t done this in years but it used to be that if you were a SaaS customer this was pre-configured for you at Global. This would only break if you override the settings in the console. I would just make sure this is set to inherit. Again this might have changed were it is no longer provided. But for my test on-premises environments my go to was always Twilio since they offered a free trial for me to just test the connections and send a few SMS messages.
https://www.twilio.com/sms
I hope this helps you!
