Top 4 Factors that Affect SMS Deliverability

Alexa Lemzy June 20, 2016
Working in an office

Text messaging has been a huge boon to businesses. Prospective customers who receive text messages show a 40% higher conversion rate than those aren’t contacted via SMS. In 2016, it’s predicted that 61% of business centres will offer SMS as a form of customer support. And SMS marketing has generated impressive returns on investment for its users.

But to reap the benefits of your SMS campaign, it’s important that your messages reach their intended destination: your customers. There are lots of reasons why your customers may not receive your messages. Here are some of the main reasons:

Grey Routes

All SMS routes are not created equal. As SMS grows, it’s become more and more common for application-to-person (A2P) messages to be sent via grey routes , which basically bounce around to different locations first before making their way to their final destination. Of course, on the way, the message may get lost or be deemed as spam and, in the end, never make it to its destination.

CEO of Dialogue Group, Perry Offer, has expressed concern not only about the deliverability of messages through these routes, but also that many of the senders employed fraudulent routing methods that allowed them to avoid paying. Perry affirmed that billions of dollars in revenue were being lost because of these routes.

Recently, groups such as AdaptiveMobile, a mobile security company, have developed tools to detect grey routes and intercept messages being carried on them. They can detect the origin of the messages and notify operators so that the operators can recover their revenue.. Ideally, messages will be either sent locally or internationally through a “1-hop strategy” that connects directly to operators to ensure deliverability.

Carrier Spam Filters

If you send a message that looks like spam, whether or not it actually is spam, chances are the carrier will filter it out and the recipient will never get it. So, how can you avoid looking like spam to ensure your messages get through? Here are some things that cause carrier filters to discard messages as spam:

  • Don’t use alphanumeric sender IDs. Most carriers assume these are spam. Use only numeric sender IDs instead.
  • Mass identical body messages. You may be doing a marketing campaign push and sending messages to your entire customer list. That’s fine, except that massive numbers of identical messages tend to set off spam alarms. So, break up the messages into different groups and vary the body message to avoid being marked as spam.
  • Create different sender IDs. Some carriers filter out messages from the same ID. To avoid this, create multiple numeric sender IDs and use a system where you randomly rotate them to avoid any user always getting a message from the same ID.
  • Include opt-out instructions. If customers don’t know how to opt out of your SMS programme, then you’re more likely to get marked as spam. Be sure to provide clear opt-out instructions to improve your reputation and avoid being labelled as spam.
  • Don’t spam. Just in case this wasn’t obvious, it’s best not to spam in order not to be marked as spam.
Mobile Tower

Phone Issues

Sometimes you’ve done everything right – you’re sure the messages weren’t sent through grey routes and you created various numeric sender IDs – but your message still didn’t get through. This could be an issue with the customer’s phone. Any of the following issues could disrupt a message from being delivered:

  • The phone is turned off. No activity can be registered if the phone is off.
  • The phone’s memory card is full. If the memory card is full, no more data is able to get through.
  • The phone is roaming. The phone is out of reach of a signal and therefore can’t receive any new messages.
  • The phone is disconnected. Lack of payment or long-term disuse can lead to a phone being disconnected.
  • The number doesn’t exist. After a period of time of being disconnected owing to lack of payment or lack of use, a phone number can be deleted from a carrier’s services.
  • It’s a landline. Sometimes you’ve imported your SMS contact list from your email list and you end up sending SMS messages to customers’ landlines. Though some countries do support SMS messages on landlines, the majority don’t. Chances are, if you’re reaching a landline, your message will not be delivered.

Sometimes, their phone is working just fine, but you didn’t manage to enter the right number:

  • The international code hasn’t been included. If you’re sending messages internationally, then you need to include an international country code in order to reach the client. People generally don’t include their international country code when filling out forms either online or in-store, and if your SMS company is in another country you’ll have to update your list to include any international codes the customers left out.
  • The international code format is wrong. This is a common mistake. Each country has its own coding system, so you may have to research the correct dialling format to reach a customer successfully.

And sometimes it’s a language issue:

  • A message that’s sent in a different alphabet (e.g. Arabic, Japanese, Chinese) that’s destined for a carrier that supports another alphabet, or that contains accents or different characters, often shows up incorrectly in the message. That can cause it to be marked as spam. Some messaging services contain transliteration tools that prevent this from happening.

Phone Number Portability

It’s possible for clients to switch from one carrier to another and still maintain the same phone number. This is very convenient to the client; however, it does come with its drawbacks. If your messages were getting through just fine with one carrier, the new carrier may decide that they’re spam and stop delivering them. The client likely won’t be aware that this is happening and assume that you stopped sending them messages.

You can get around this by doing a network look-up for your client list, but it can be an expensive and laborious practice. Some carriers don’t support this, making it even more difficult. Unfortunately, chances are that if this is why your client is no longer receiving your messages, it can be difficult to recover the former level of message deliverability.

Avoiding grey routes, avoiding looking like spam, and making sure you have the correct country code and language tools – all these steps will help you improve your deliverability rates.

Alexa Lemzy


Customer support person. Interested in customer success, growth, marketing and technology. Passionate about content, reading and travel.

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