I signed up for silent-link yesterday too. My impression is that it's cheap, slow, mobile internet service for people who roam about the globe. The IP address they assigned me was from Warsaw, Poland of all places.

But their voice and SMS, even by their own admission, is done on a "best efforts basis," which is just a polite way to say "it usually won't work."

Even if you catch it on a good day and it works, the service is inbound only. You can't send. So if your bank were to ask you to approve a transaction by responding with "YES," you won't be able to do so.

Someone will likely recommend that you try a VOIP service like OpenPhone. That'll fail too. Although their SMS works, it doesn't work with banks. Banks won't send SMS to VOIP services. At least that's the case with Bank of America and other major US banks.

The only thing I've found that works is to buy a cheap, prepaid flip phone with cash, in my case from Verizon, though you can probably buy online for Bitcoin. Then you can pay for it each month using BitRefill. It'll run at least $35 per month.