Sending SMS to Numbers with Five- or Six-Digit Short Codes Are Bounced

The error message I receive is, "Error: this message was not successfully delivered." This happens whenever texting my bank, or other business services that use short codes like this (e.g., 50292, or 22000) for customer interaction. I can receive their messages but I cannot send back any replies to them. They always fail with the same stated error message. I happen to be using a Sprint Samsung Galaxy S5 running on stock firmware. For SMS messaging I've preferred to use Google Voice (it's linked up to my Sprint number and handles my voice-mail too), but the error still happens on the stock SMS messaging app.