What features does this offer in comparison with just signing up for a Twilio number for $1/month? I've always just used their message logs UI to look at inbound messages for 2fac.
So oneway.tel is basically just the Twilio messages/calls/recordings log in a more convenient interface, with Google/FB auth (which is convenient for me).
If you're already experienced with Twilio configuration and their console then $5/month may not be worth it.