Please configure the APN in your device to be "em" (just the two letters, without the quotes).
Please be sure to enter the exact name of the APN as shown above when you program it in your device. Any discrepancy will result in the data service being unavailable to your device (the device might still be able to attach to a network, but a data connection cannot be established).
If your device asks for username and password while configuring the APN settings, you can leave them blank, the network access is automatically authenticated using the SIM card secret keys and strong cryptographic algorithms.
Also, please make sure you have data roaming enabled on your device.
Issues with short APN
Some devices do not accept a two letter APN. In some cases, the APN needs at least 5 letters / digits or more. In this case, you can try to add *, # or even blank characters. Examples:
Note that this is a workaround and not a solution that will work on every device.