Sprint HTC EVO 4G - Data not using Wi-fi when roaming - Configuration Issue with mobile network
I feel a bit like a beta tester for Sprint, but I found (based on my recent invoices from Sprint) that there appears to be an issue with the configurations for wi-fi and mobile networks on the HTC Evo 4G phone. (The configurations can be found in home -> menu -> settings). This problem was found when traveling to Canada, and I'm posting it in an effort to save other 4G users the pain of a very expensive bill when they think they're connected to a wi-fi network, but are actually streaming over an international cell network.
In the settings menu, there is a wi-fi setting, and a mobile network setting. I found that if both are turned on (checked), the mobile network setting CAN take precedence, even though it clearly states under the setting that the configuration is designed to 'use phone for data connection when Wi-Fi is unavailable'. I ended up with a $450.00 additional data charge on my phone in the month of November because of this issue. Here's how to avoid it.
When traveling internationally, allow the phone to have 'wi-fi' enabled (so you can use the wireless network at the hotel, apartment, etc), but uncheck the 'mobile network' flag. If you do not unselect the mobile network flag (even though you have wi-fi enabled) you will incur unnecessary charges for data.
I spent about 3.5 hours on the phone with Sprint today, and finally was able to get acknowledgement of this issue through level 2 advanced support. (Thank you Nathanial). I would strongly recommend that Sprint work with HTC to have the mobile network configuration description revised, and am happy that the level two advanced tech support folks understand this issue.