Registration error

After I've used in the past few weeks Whatsapp, I have now installed Mitakuuluu3 - but every time my registration failed.

I made the following steps:
- Closed Whatsapp
- Installed Mitakuuluu3 from openrepos
- Failed request registration code via SMS (registration error, Reason: No cell roulés for sending SMS Caused by your operator ...)
- After 1 hour new attempt, this time by call - failed, same error message

- Uninstalled Mitakuuluu3
- Restarted the phone
- Reinstalling Mitakuuluu3
- Failed request registration code via SMS (registration error, Reason: No cell roulés for sending SMS Caused by your operator ...)
- After 1 hour new attempt, this time by call - failed, same error message

Has anyone an idea what is going wrong or what mistakes I might have made ???

Thanks in advance.