How can you be charged for data usage if you cleared your APN data? At least where I live, you have to set a username and password there (and actually sign up for a data plan with the carrier before you can actually download data :-P).
Originally Posted by KlaymenDK
The general consensus is that if you intentionally misconfigure your APN settings, you won't incur any charges. This is what people do when travelling to avoid data roaming.
I don't know if a 'blank' APN name would be the best option; something decidedly incorrect may be more bulletproof. This is what the "APNdroid" app handles for you.
You don't need an app for that, there's a "Data roaming" setting under "Wireless controls" -> "Mobile networks" to avoid data roaming costs.