How Do I Resolve "Error 351" or "Invalid Destination Address"

There are a vast number of error codes that carriers send back to TextPower to indicate why messages didn't get delivered.  One of the most frustrating is an "Error 351" or "Invalid Destination Address Value."  What does this mean and how can you resolve it?

What this typically indicates is that the carrier has blocked short code messages from being delivered to this particular phone number. They may also be blocking users from sending messages to short codes. If this is the case the users will have to contact the carrier to ask them to "remove the short code block."

Why does this occur? There are a few potential reasons:

  1. It is possible that the number you are sending to is not a mobile number but rather is a “VoIP” line (voice over IP), the most popular type of “landline” now being purchased by homeowners that do want a landline.  These numbers can potentially receive text message even though they are not assigned to mobile devices.  The national cellular database does not reject the numbers so it is possible that after a lookup they will appear to our system as a mobile number.  When trying to send to that number, however, we will receive the “Error 351” message from the upstream aggregator that the number is not assigned to an actual mobile device. 
  2. If the customer has recently ported their mobile number from one carrier to another (e.g., AT&T to Verizon Wireless) the carrier may not process text messages to or from short codes - this does not affect "peer-to-peer" messaging which is when one mobile number sends to another mobile number - until after the billing has been established or the final details of the port are completed.  
  3. The phone may be on a prepaid plan and does not have sufficient credit to receive additional messages.
  4. T-Mobile does not deliver text messages to their resellers' numbers.  There are exceptions to this and it does not always apply in cases of T-Mobile errors but it is a strong possibility if the number in question is on either T-Mobile's direct service or through one of their resellers. 
  5. The number may have been deactivated for non-payment at one time and even subsequent to the past due amount being resolved.
  6. At one time the number was on a plan that restricted the reception of messages from short codes. 

There are other miscellaneous reasons why a "short code block" may have been imposed but it can be a mystery even after talking to carriers.  

How do we resolve this error?

TextPower can work behind the scenes on behalf of the mobile user to remove the short code block.  The most direct solution, however, is often for the customer to call their carrier's customer service and ask about it, which almost invariably results in the removal of the block.  

Before directing these users to do contact their carrier, however, it would be helpful to have them text "HELP" to the short code to which they are assigned to and see if they get TextPower's standard response. If they do receive it, it indicates another problem but if they get no response at all then we will be pretty certain that this is on the carrier side and requires the user to request that the short code block be removed.

These procedures resolve 99% of these errors.  If after taking all of these steps the problem still exists please contact TextPower directly.


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