I'm trying to send an SMS with Messenger on my new Nexus 5X running Lollipop, but sending always fails with Can't send message on card 1, error 21. Receiving SMS and making phone calls works fine. What's going on?

  • 2
    Please check message service center settings for SIM1/2 and uncheck use same service center for sending/receiving messages in Message settings. This is the most common problem if everything else is fine. Commented Jan 10, 2016 at 2:59
  • I got this error when my phone bill was overdue. Commented Jan 31, 2017 at 1:07

2 Answers 2


Most likely the destination phone number is formatted wrong, which can happen particularly when importing contacts via third-party tool.

In this particular case, I used My Contacts Backup for iOS to export my contacts to VCF, then imported from Gmail. In the process, some numbers were wrongly formatted as +61 0 4xx when they should be just +61 4xx, causing the highly uninformative error message above. (The 21 error code actually comes from the operator's network, and has nothing to do with Android as such.) Removing the extra 0 solved the problem.


If above mentioned methods are not working, you may try installing 3rd party SMS applications (eg., EvolveSMS) instead of Google messenger. Hope it helps.

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .