Bluetooth connection not working on US Nokia phones from J2ME Midlet (MIDP

Question

Hi All,
We are developing a J2ME midlet (MIDP 2.0 ,CLDC 1.1)which makes bluetooth connection to other devices.The bluetooth
connection is working perfectly on indian nokia phones with Airtel as carrier.But when we deploy the same midlet on Nokia E71
US phone with carrier as AT&T ,the bluetooth connection is not working.The sample code is as follows:
public void run(){
try{
StreamConnection connection = (StreamConnection)Connector.open(btConnectionURL);
// open an input stream to get some data
InputStream in = connection.openInputStream();
byte[] serialData;
readData = true;
while(readData == true){
int lengthavai=0;
lengthavai = in.available();
if(lengthavai > 0){
serialData = new byte[lengthavai];
int length = in.read(serialData);
System.out.println("data read: " + new String(serialData));
dataViewForm.append(new String(serialData));
in.close();
connection.close();
}catch(IOException ioe){
ioe.printStackTrace();
when we try to connect on US Phones],the execution hangs at the following line of code:
StreamConnection connection = (StreamConnection)Connector.open(btConnectionURL);
No exception is caught.
Our midlet is not signed.
In the Forums it is said that the problem is with the unsigned midlet.AS some of the US carriers block the secure API usage
on Unsigned midlet.
But our question is, if we buy a code signing certificate from Verisign or Thawte and sign the midlet, will this problem be solved.
Any other alternative solutions for this ???
Immediate help will be appreciated.
Thanks,
Yash

Answer 1

You might want to read this before buying a certificate:
http://javablog.co.uk/2007/08/09/how-midlet-signing-is-killing-j2me/
It's not my blog, but I pretty much agree with what it says. Unfortunately the network operators can control the access 3rd party trusted certificates have, so even if you sign with Verisign for example, the signed midlet may not have any more privileges than an unsigned midlet, depending on network. They do this so that only midlets signed with one of their own certificates have unrestricted privileges forcing anyone who wants a useful application to buy it from the network instead of downloading an equivalent freeware version from Getjar for example. Some networks are worse than others, so signing your midlet will allow it to work on more phones than an unsigned midlet. I think Verisign have some info on AT&T on their website.
The whole MIDP specification for security is a joke, IMHO. I don't mind unsigned midlets flashing up a warning once during an application. Writing 20 files, for example, will give 40 security warnings for reading writing data which is ridiculous, as the user obviously either trusts the app or he doesn't. No one runs an app that they only sometimes trust.
As far as I know the only mobile manufacturer so far to see sense is Sony Ericsson. All of their new phones from Java platform 7 onwards allow unsigned applications access to the file system, bluetooth etc with just one warning when the applications starts.
Andy