SMS delivery troubleshooting - Ortto help

Overview

In this article, you will find a comprehensive guide on how to effectively troubleshoot SMS delivery issues.

Delivery issue investigation

Delivering SMS messages involves multiple factors, and just like with email, delivery issues can arise from any one of the elements listed below:

Sender practices:

From the current message being created to messages sent previously, send-practices affect a senders ongoing deliverability.

Message-build platform (Ortto, in this case):

Errors can occur when the message-build platform must package and hand off the SMS traffic to the message-send platform.

Message-send platform (Twilio, in this case):

The message-send platform must be able to accept the traffic from the message-build platform, verify everything is in order for delivery, and be able to properly connect and communicate with each carrier, for each recipient.

Recipient carrier (and related systems):

The recipient carrier must be able to accept the traffic from the message-send platform, verify everything is in order for delivery, check reputation and block settings, and be able to properly connect and communicate with each recipient’s device.

Recipient device:

The recipient’s device must be able to connect to the carrier and receive the message.

Spam filtering

SMS delivery issues can also happen due to perceived spam-like activities, not just technical problems. While some carriers are starting to experiment with spam filtering for SMS, most don’t have this feature yet.

In general, if a carrier detects a message of questionable quality, it will simply block delivery to the recipient. Fortunately, error codes for these failures can help identify and resolve such issues.

Bounce reasons

The Reason field under the Bounced SMS activity may display the following bounce reasons for undelivered SMS messages:

Unknown destination handset	Meaning: The destination carrier is reporting that the to (intended recipient's) number is unknown, or no longer in service. Resolution: Communicate with the subscriber via other channels to verify number is accurate and active.
Unreachable destination handset	Meaning: The destination carrier is reporting the to number is unreachable - the device is likely powered down, out of a service area, or may not accept your messages. Resolution: If the issue persists with the next sending attempt, communicate with the subscriber via other channels to verify number is accurate and active.
Carrier violation	Meaning: The destination carrier is filtering out your messages for delivery. Resolution: Check your content in comparison to carrier regulations based on recipient region. Please find guidance on this below: US & Canada. International guidelines by country.
Message blocked	Meaning: Your message has been blocked from reaching the destination. Resolution: Communicate with subscriber via other channels to verify number is accurate and active. Also, check your content in comparison to carrier regulations based on recipient region and look for a trend in carrier-related recipients with the issue. If the issue is ongoing, reach out to Ortto’s support team for further help (click Support within the Ortto app to submit a ticket or email help@ortto.com).
Landline or unreachable carrier	Meaning: The destination is a landline phone, or the destination carrier can’t be reached. Resolution: If the issue persists with the next sending attempt, communicate with the subscriber via other channels to verify number is accurate and able to receive SMS communications.
Unknown error	Meaning: The destination carrier has returned a generic error message. Resolution: Check your content in comparison to carrier regulations based on recipient region and look for a trend in carrier-related recipients with the issue. If issue is ongoing, reach out to Ortto’s support team for further help.

NOTE: When connected to TallBob, the Reason attribute for Bounced SMS activity will be available in both Ortto and your TallBob account.

Investigation tips

Here are some questions whose answers can help you identify the source of any delivery issues:

What is the error code for the recipient?
Is there a trend in the error code/carrier/region or is it local to individual recipients?
What is different with this send than previous sends?
Is the content in alignment with regional regulations?
Is the content longer than 320 characters?
Are shared domains being used in links?
Are emojis or irregular capitalization/punctuation used in the content?
Is your sender ID up-to-date?
Have you made any changes to your number or sender ID recently?
Have these recipients expressly opted in?
Have these recipients received clear opt-out directions?
Are opt-out requests being honored?
Are you seeing regular engagements that meet our advised thresholds?

Delivery speed issues

The delivery speed, or messages per second (MPS), from your phone number is limited and depends on your Trust score and the declared use-case category assigned to your company’s SMS traffic.

For details on what your limit is based on Trust score and Categorization, please refer to this Twilio article.

NOTE: Trust scores are static and not regularly updated.

If you receive a low Trust score, Twilio will do their best to offer guidance on possible causes or resolutions for a low score. If this applies to you, please contact 10dlc-onboarding@twilio.com and include the Account SID corresponding to your A2P registration.

The appeal is free if you received your score less than 45 days ago. For trust scores received more than 45 days before the appeal request, a secondary vetting fee of $40 is required.