I've been searching for months for a credit card reader that works with my pre-paid Straight Talk cell phone plans from Wal-Mart. I want to be able to accept credit cards securely through my phone. These results are shared with you. Companies who have confirmed their credit card readers will go on these continuously updated lists:

DO work work with specific pre-paid cell phone plans

1. Square Register
"Square Register will run on most Android devices with the following features:
- Requires an internet connection at all times
- Running Android 2.2 or higher, however we currently do not support Android 3.0 (Honeycomb)
- Screen size specified as Normal or Large
- 3.5 mm headset jack (which includes a microphone input)
- GPS
- Touchscreen display
I’d recommend confirming with Straight Talk or your pre-paid cell service provider that a strong internet connection is provided." ~ Square Tech Support


Do NOT work with ANY pre-paid cell phone plans

1. PayPal Here

This is a real shame, because Straight Talk is becoming more and more popular as it is "the best plan on the market" as long as your within and traveling within Straight Talk coverage.

I read one reason certain phone don't work is due to an inablity to securely transfer data. I'm not sure why they don't accept certain cell phone service providers (especially nationally available ones).