While discussing with SNAP Mobile team members I was told that they have generated a test midlet to evaluate the compatibility of the device/network combo with SNAP Mobile. From the "SNAP Mobile API: Compatibility Test Instructions" document (both are available in the SDK download)

"SNAP Mobile ... is designed to work on all MIDP 2.0 devices. However, there has been some variance among different device types and different manufacturers. In addition, some operators have port and/or APN settings configured to block the SNAP Mobile API, or any other third-party game data packet, from going through a gateway. In order to protect developers from developing SNAP Mobile games on non-compatible devices and networks, Nokia is providing the tool to verify the compatibility."

The doc says that the testing one device takes 15 minutes, and that's about right - unless you need to configure the network settings from the beginning, in which case you need to reserve some more moments.

I spent some time checking a couple devices on Cingular network (E61, 5500, 6131, 6280). I had some problems getting the results on the Series 40 devices - the midlet seemed to fail numerous times and complain about network timeouts (I guess this is because the HTTP test failed on both of the devices), until I finally got the results out:

If you do any SNAP Mobile compatibility testing, please send the results to SNAP Mobile team. Again a snippet from the same doc:

"Nokia also encourages developers who conduct API compatibility tests to submit their test results, comments, and feedback to Nokia. Nokia will compile this information and share it with other SNAP Mobile developers. By doing this, all SNAP Mobile developers benefit collectively from this data, because it helps make the connected games market larger and more robust."