SMS sent from a Toll Free # are not delivered to some T-Mobile customers

  • 22 September 2020
  • 2 replies


Hi there,

Looks like I’m not the only one with this issue, but I havent been able to find a solution or an answer so I figured I’d ask again. 

My company sends scheduling related notifications to employees when shifts become available or time’s change, etc.  We used to use a shortcode for this, but were advised that we could swith to our Toll Free # since we werent sending marketing email and all of the users are known and willingly opted into the system.  99% of the time we have no issues and everyone receives their notifications as they should.  Unfortunately that 1% of the time are always T-Mobile customers.  The messages return the following message from Twilio: Error 30005 "Message Delivery - Unknown destination handset"

This only affects a small number of t-mobile phones and all the messages are sent form the same number.  Users have called T-Mobile to confirm that they do not have any message filters activated on their account, but we have not been able to resolve this issue.  A recent user was receiving notifications in March this year, and then they stopped, all receiving the same error.  We have confirmed that these users can receive regular messages, and can receive messages from our system on a local number.  All email-to-SMS messages to t-mobile numbers are being blocked as well,  so we cannot offer that as a solution. 

Is there any reason why some plans or numbers would filter messages from a toll free number while others wouldn’t?  That’s the only explaination I could imagine.  If so,  is there any way to work around this?  From reading some of the other questions on here, I’m sure someone will suggest going back to the shortcode, but we honestly had just as many, if not more issues with carriers blocking our short code before we switched.

2 replies


did you get any help with this?