Here, we'll outline the common reasons that your SMS messages aren’t being delivered and Optimove’s process for resolution.
Why did my SMS message not deliver?
The number listed for the user is invalid
If the deliverability issue is exclusive to just a small percentage of your users, or a select number of your customers’ mobile numbers, then it may be that the mobile numbers on file for these users were incorrectly added at opt-in. These numbers could be incorrectly formatted, missing a country code, or non-operational.
SOLUTION: Much like email, we recommend a mobile number validation service to help verify and/or standardize the phone numbers that are having deliverability issues according to country-specified formats. These 3rd party services can also help to reverse append mobile numbers using your user’s name and postal addresses.
Example 3rd party solutions include:
- Experian’s phone validation tool
- ClearoutPhone
The number is listed on a “Do Not Call” list
Both landline and mobile numbers can be listed on the National US Do-Not-Call list, and other countries and regions may have these as well. If your user(s) have added their mobile number to one of these lists, you may be prohibited from sending messages to them.
SOLUTION: Check your nation’s or region’s Do Not Call registry for your country and ensure that none of your users have opted in for this suppressive service. If you find any of your user’s mobile numbers within these Do Not Call registries, it’s important to update their “Allow SMS” attribute to reflect the inability to deliver SMS messages to them.
Additionally, when signing up users for your SMS program, consider asking them if they have signed up to receive promotional text messages or if they are currently on a Do Not Call registry - prompting them to reflect before providing their number.
Your SMS message is too long
SMS text messages are limited to 160 characters per message. If your message exceeds this character limit, it could result in being sent as two separate messages or result in a deliverability issue. SOLUTION: Work to keep all of your outgoing SMS messages concise - focusing on your key objective and call to action, so that SMS messages are likely to reach your intended target audiences and engage. If your SMS messages are running long in character length, consider taking stock of what you are attempting to say in your message and look for opportunities to break it up into multiple, shorter SMS text messages as part of a strategic SMS or multi-channel stream.
Additionally, SMSTarget G will always show you where your character length stands against the 160 character max allowance. If you exceed the 160 character limit with your single SMS text message, SMS’s template creator tool will share the total number of messages needed to deliver your content successfully.
The quality of your mobile number list is poor
As with email, the quality of your Target Group and mobile database can dramatically impact deliverability performance. Are all of the mobile numbers users have opted in with valid numbers? Are the mobile numbers accurate? Based on the country the user/customer is from, are they formatted properly? Having the correct mobile number for each user and making sure the numbers themselves are formatted properly is key to SMS message delivery success.
SOLUTION: Much like email, we recommend a mobile number validation service to help verify and/or standardize the phone numbers that are having deliverability issues according to country-specified formats. These 3rd party services can also help to reverse append mobile numbers using your user’s name and postal address.
Example 3rd party solutions include:
- Experian’s phone validation tool
- ClearoutPhone
The number does not accept text messaging
Some phones are not capable of receiving SMS text messages - whether that’s because they’re an older model or a landline, or they have messaging services deactivated.
SOLUTION: At opt-in, ask users to provide the mobile number of a newer mobile device that can support/accept SMS messages. Moreover, for mobile numbers that are not receiving SMS messages properly, but we have the user’s email address on file, consider an automated or triggered campaign to deliver an email asking the user to update their mobile number to one that’s valid and for a device that can accept SMS text messages. If you have deployed a multi-channel campaign with the objective of having the user update their mobile number on file and receive no response, consider updating the user’s account setting so that “Allow SMS” is set to false.
Your message was flagged as Spam
When either SMS or the aggregator notices that your SMS message includes specific words, language, or terms that may trigger the spam filters of providers by region or country you’re attempting to deliver to, your message will be flagged as spam, and your message will not be delivered. SOLUTION: Make sure you’re up to date on all content regulations by region or country of users that you are including in your SMS Target Groups.
If you’re unsure of which words, language, or terms may trigger spam filters (i.e., using all capital letters, excessive use of punctuation marks, etc.), please reach out to Optimove’s expert SMS Marketing Manager for specific examples, compliance details, regulations, and more on a country-by-country basis to help in your SMS marketing strategies.
Technical Troubleshooting & Deliverability Benchmarks
What’s considered a “good” SMS delivery rate?
While different aggregators offer different delivery rates, generally speaking, a good SMS delivery rate of 90% or higher is what you should aim for as a KPI for success. Anything less than 90% may indicate that your SMS messages aren’t reaching their targeted audiences. It's important to note that deliverability isn't measured by total API calls or messages sent. Message Deliverability strictly measures how many messages are delivered versus the number intended in a defined time frame.
This key difference means that your logic can implement fallbacks and use messaging auditing features to increase deliverability, even if that requires additional API calls and redundant logic. As SMS deliverability strictly focuses on intention versus result Ex. A campaign is sent to a list of 5000 subscribers with the condition that they are excluded if they have already received a message in the last 24 hours. If 200 subscribers meet this criteria and do not receive the message, it was due to intention and not a deliverability issue.
What is the importance of your SMS deliverability rate?
SMS deliverability refers to the metric that shows marketers what percentage of their sent SMS messages successfully reach recipients. Your open rates can only be high if your messages are delivered. Therefore, this is the most fundamental metric to track when measuring the performance of your SMS marketing campaigns. That number is, of course, pointless if your messages don’t deliver. Your SMS campaign success largely depends on the number of texts successfully received. The higher the rate of deliverability, the more successful the SMS campaign is likely to be.
What causes a delay in SMS message delivery?
Typically, a delay in the delivery of your SMS message can be attributed to network congestion. When too many people are using a network at the same time, it can slow down or prevent messages from being delivered properly. This is more common during peak hours, rush hour, or during major seasonal events, or during events such as concerts, sports games, etc., by region or country. Another possible cause for a delay in message delivery is when the target audience’s carrier blocks a sender’s number. If the user’s carrier doesn’t recognize the sender’s number, it will most likely block the message from being delivered. This typically happens when sending messages to someone from another country.
SOLUTION: If your list is large enough, you may want to consider transitioning to a short code phone number to improve delivery speed and consistency.
Why would an SMS message be marked as Spam?
There are many reasons why an SMS might be marked as spam. Some reasons could include that the sender's number has not been added to the recipient's contact list. If the recipient doesn't know the sender, there's a good chance the message might be marked as spam. If the SMS contains too much marketing or advertising content and is nothing more than one big sales pitch, it may also be considered spam and automatically blocked by many carriers. Finally, if an SMS is sent to many people at once, it may be marked as spam because it can clog up inboxes and cause annoyance.
SOLUTION: Incentive recipients to save the sender’s contact information on their device. If the option is available, send a virtual contact card after signup that allows them to easily save this information with one click.
Is SMS message delivery guaranteed?
While 100% delivery is not guaranteed, SMS delivery is typically quite reliable. Even when messages are delayed or don’t make it to your target user’s phone when your SMS campaign is deployed, the message is usually successfully delivered within a few minutes of the original send time. Some common causes might include high message volume or carrier delays caused by high-traffic events like BFCM. Take a look at the “What causes a delay in SMS Message Delivery” for more information.
You’re in violation of SMS compliance by region or country
Using a reputable SMS delivery service, such as SMS, is one of the best ways to avoid rejected messages, but you also want to be on the right side of the law. Optimove stays ahead of industry changes and SMS compliance rules designated in multiple regions across the globe. For instance, phone numbers are collected from customers; you need their direct consent before sending any texts, just like with email marketing. Some compliance issues may cause deliverability issues, but it is imperative that they are identified and corrected as they can lead to much larger issues down the line, such as carrier bans or phone number shutdown.
SOLUTION: Check compliance documentation or consult with your aggregator about potential issues with banned language or topics, missing required opt-in or opt-out language, and confirm your message wasn’t sent during a possible non-compliant time of day or holiday in the region you targeted.
What is a Short Code, and do I need one?
A shortcode is a 5 or 6-digit phone number that is used to send text messages at scale. People opt into SMS marketing programs by texting a word or phrase known as a "keyword" to a short code. They are meant to be shorter than normal phone numbers to make the opt-in process easier. Additionally, shortcodes are capable of sending extremely high volumes of text messages in a short period of time. This makes them the optimal choice when looking to reach large audiences. Short codes are the most expensive, with a typical monthly cost between $500 and $1,000, depending on whether it’s a random or vanity code. While messages sent from normal 10-digit numbers are subject to carrier spam/content filters, SMS short code texting is not typically filtered.
Why did I receive duplicate SMS Messages?
If you received duplicate messages, it may be because your phone number is connected to multiple Customer IDs within Optimove, and both were included in the campaign’s Target Group.
SOLUTION: Scrub the customer list for duplicate SMS numbers and ensure that each phone number is only attached to one Customer ID.
Are there funds in my Aggregator Account?
If you use prepaid payments with your aggregator, you may need to add more funds. If your account balance reaches zero, your messages will not send out.
SOLUTION: Top up your account balance before scheduling future SMS campaigns. You can also see if automatic payments are available in your region to ensure your account never runs out of money.