Bug 978130 - [FDN] Misleading SMS message

If the SMS call center is not in the FDN list, no SMS can be sent
 - no matter if the recipients are in the FDN list or not.
Here is a less misleading error message.
Merge pull request #18124 from arcturus/fdnMessage-bug978130

Bug 978130 - [FDN] Misleading SMS message