The problem
You are unable to book an easyMobile roaming option via SMS reply – request unsuccessful.
The reason
When sending an SMS booking request, some Android SMS messaging apps will automatically add Germany's international prefix. For example instead of sending your request to 70127, your SMS is instead sent to 004970127. Unfortunately this is not the correct number and will invalidate your reply and your booking request.
The solution
For Samsung phones, change your default SMS app from Google to Samsung Messages which does not add the country code. For other Android phones such as Nokia, Sony, or Motorola, deactivate the assisted dialing feature.
Samsung phones
To change the default SMS messaging app to Samsung Messages go to your general phone settings: Settings --> Apps --> Messages, then select Samsung Messages and set it as the default SMS app. Please note that both the Google and Samsung apps are called "Messages", however the Samsung icon has three white dots, see below.
You can also verify which app is which by looking where the app was downloaded in the app details. If the app was downloaded from the Google Play Store it's the Google app, and if downloaded from the Galaxy Store, it's the Samsung app. Again, be sure set the Samsung app as your default SMS app.
After making Samsung Messages your default SMS app, resend your booking request with the appropriate text to the number 70127.
Other Android phones | Nokia, Motorola, etc.
Open the telephone app on your phone and tap on the 3 dots at the top right of the screen, then select: Settings --> Assisted dialing --> deactivate Assisted dial.
After deactivating the assisted dialing feature, open your messaging app and send a new message with the appropriate booking text for the desired roaming option to the number 70127.