xMatters and SMS Best Practices

There’s no denying that SMS is a popular and (mostly) effective communication method. We’ve discussed its advantages and shortcomings in this space before, but it might be helpful to go into a little bit more detail and provide some tips and tricks for getting the most out of SMS and xMatters.

Why now?

We’re making some much-needed changes to the way that xMatters On-Demand handles longer SMS notifications. There are a number of reasons we’re doing this, largely due to SMS carriers and delivery providers, but mainly because of the limitations inherent to SMS as a notification medium.

What’s wrong with SMS?

We could go on (and on and on) with all the shortcomings inherent to SMS, but if we had to point to one limitation that makes it so hard to use it would be the fact that messages are limited to 160 characters, or even fewer if you’re not using 8- or 16-bit characters. This doesn’t mean that you can’t send longer messages, but it does mean that they require some special handling.

When xMatters sends out a longer SMS, the carrier responsible for handling and delivering the message breaks it into chunks of 153 characters (for 8-bit characters) and sends each segment as a separate message. The rest of the message space is reserved for information that carriers use to route the message and then reconstruct it on the recipient's device. This means that a text of just 500 characters – about the length of this paragraph – gets broken into four separate segments, each of which is sent as an individual message and reassembled when they get delivered to the device. Well, usually.

If any one of these segments gets lost (“various studies have shown that around 1% to 5% of messages are lost entirely, even during normal operation” - Wikipedia) or interrupted or delayed, the message can’t be reconstructed properly on the target device. If the recipient is lucky, the remaining pieces are delivered separately or reassembled in the wrong order. If they’re unlucky, the entire message just gets discarded.

What’s changing?

Limits are being placed on the number of segments that xMatters can send for a single message. The exact limit depends on a number of factors such as carrier, region, and provider, but most customers will see their SMS messages restricted to a maximum of three segments for 8-bit character messages, and 7 segments for 16-bit character messages. 

What this means is that a message limited to a maximum of three segments cannot contain more than a total of 459 characters (153 x 3). And that includes all the responses, regulatory text, etc. If that limit is reduced by a particular carrier or other provider to two segments, then the maximum number of characters drops to 306. (We actually strongly recommend that customers try to keep their messages under this lower limit, just in case.)

So what happens if a message is over that limit? Well, to carry on with our 3-segment example, any characters beyond the 459th are truncated and the message simply ends there. There's no indication given that the message is shorter than it should be, by the way - the message just stops.

In certain respects, these limits are actually a good thing. Most large networks and cellular carriers treat SMS messages as low priority, meaning that your texts are the first things dropped when the service gets busy with other traffic. By limiting how many parts our messages can have, we can all help make messages much more likely to reach their destination.

Best practices

Even with all the issues, limitations, unreliability, and maze of regulatory organizations associated with it, SMS remains overwhelmingly popular as a communication tool. And really, we understand its appeal – when it works, it really works well.

So here are a few ways to make sure SMS works for you.

Tip #1: Don’t use SMS

Okay, maybe it’s not fair to start with this one, but really: the xMatters mobile apps are better in every way. They don’t rely on unpredictable aggregators or carriers, they don’t charge recipients for each message they receive, they’re WAY MORE reliable, and they offer so many features that SMS doesn’t:

  • Modern and evolving technology
  • Rich-text formatting
  • One-click responses
  • Stable message routing
  • Long message support
  • Multi-byte character support
  • No extra regulatory content

Don’t forget that you can access xMatters information and special features right from your device:

SMS is good for many things, but it's not the best way to communicate critical alerts. Switch to the mobile app (for iOS or Android) and instantly improve your overall experience.

Tip #2: Don't use SMS for long messages

While the restricted length inherent to SMS is often viewed as a limitation, there are ways to make it into something of a benefit. You can take advantage of the restriction to keep your SMS messages short and to the point, and only include the most important information. If your messages are routinely coming out longer than 306 characters, try evaluating the content and  see whether there's anything extra that doesn't actually need to be there. You might find that if you strip out the unnecessary filler, you can get them under that magic 160-character mark!

Also, remember that really long, detailed SMS messages can be much harder to read. If your messages are as detailed and lengthy as an email, you're really not getting the most bang for your SMS buck.

With SMS, shorter is ALWAYS better.

Tip #3: Be mindful of additional information

When building out your SMS messages, keep in mind that some carriers require additional regulatory language on every single SMS message. Imagine receiving this message:


That’s 42 characters worth of regulatory language for 22 characters of actual message. And we’re not adding “Powered by xMatters” as part of some poorly-timed marketing effort – the carrier requires it. Exactly how much of that gets added depends on the carrier or aggregator responsible for delivering the message to the recipient so it’s difficult to predict, especially when some recipients of the same message may have different carriers.

Tip #4: Remember the response options

Similar to the previous tip, remember to leave some space for the response options that get added to the end of the message when it is sent. These can be difficult to predict as the number associated with each response will increment over responses. Oh, and depending on where the message is sent from and where it’s sent to, it may require an additional reply number:


You can mitigate this a bit by keeping your response options short. Just make sure no one mistakes “Esc” for “Escape” instead of “Escalate”.

If you're curious about what happens if the responses cause a message to go over the maximum character limit, then there's some good news. The response options will always be shown in full, but the message body will be truncated to make room for them.

Tip #5: Be wary of special characters

Not all characters are created equal. Some special characters take up more than one spot, so the actual character count of a message might be different from what it looks like in the editor. In addition, some carriers might strip out any special characters or replace them with a different character or empty space. (Oh, and because this will definitely matter to some people: this applies to emojis, too, except they still take up two spots.)

This issue is common for anyone using a word processor or other rich-text tool to compose their messages before copying and pasting them into xMatters. Many programs, such as Microsoft Word, offer an auto-correct feature that will automatically replace certain combinations of characters:


If you usually compose messages using Word, make sure you disable any of the AutoCorrect settings that have to do with special characters – and keep an eye out for the AutoFormat settings, too. Those quotation marks can really add up:


Pro Tip: An easy way to double-check for special characters is to paste your message into a non-rich-text editor such as Notepad first, and then copy THAT content into xMatters.

Also, if you're using a word processor to compose your texts, you're probably making them too long, and should consider saving all of those details for a format more suited to lengthy messages.

Tip #6: Be selective when adding properties

We know it’s tempting to try and pack as much information into a notification as you can, but with the squeeze on characters, you might not want to include the 1000-character “Summary” field of an issue in every SMS notification.

Consider the properties for each SMS message carefully and try to anticipate which ones would be most useful in the short format available.

Tip #7: Add your own!

Have you come across anything you've found useful when configuring SMS? Let us know in the Community and we'll add it to this document.


xMatters Product Management

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