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SMS character limit: write Canadian alerts that fit one text

One text holds 160 plain characters. Most alert emails are far longer, so they split into several parts and use more message credits. Keep four things: what failed, where, how bad and when. Cut the rest, and almost any alarm fits the SMS character limit for alerts.

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The problem

A 900-character alarm email

  • Repeated labels, dates and point paths
  • A footer nobody reads at night
  • Splits into 4 texts on the phone

The fix

One clear text

  • What failed and where
  • How bad and when
  • Fits in 160 characters
Illustration: the problem, a 900-character alarm email, next to the fix, one clear text.
  • One plain text holds 160 characters. Leave about 30 for the Welco: start and the opt-out line.
  • Keep what failed, where, how bad and when. Drop labels, footers and repeated dates.
  • Square brackets count as 2 characters each, so keep tags short.
  • One emoji, curly quote or degree sign shrinks the limit to 70 characters, so use plain symbols.
  • Set the trim once as a rule, then test it before the next real alarm.

Why alert emails blow past the limit

Alarm systems write emails for a desk screen, not a phone. They repeat the site name, the full point path, the date twice and a block of legal text. None of that helps the person who has to drive to the site. It is a problem most of our SMS alert guides come back to.

A text has a hard ceiling. Past 160 plain characters, the phone gets the message in parts, and each part counts as its own text. The full math is in our guide to SMS segments and the 160 limit.

The real cost of a long alert

A 600-character alarm becomes four texts. That is four times the credits for one event. On a busy night with dozens of alarms, the waste adds up fast.

Long texts also read badly. The key fact can sit in part three, below a lock screen preview that shows only the first line. Putting the key fact first is also one of our alert texting best practices.

Where the extra characters hide

  • Field labels such as Notification Type:, Point Name: and Alarm State:.
  • The same time written two or three ways, often with seconds and a time zone.
  • Long point paths like Campus/Building 2/Floor 3/AHU-3/RAT.
  • Signatures, disclaimers and "do not reply to this mailbox" footers.

How many characters can one alert text hold?

One alert text holds 160 plain characters before the network splits it. That ceiling is set in the phone network's alphabet standard, 3GPP TS 23.038 (ETSI version 18.0.0, May 2024, read October 6, 2026).

Once a text runs long, every part gives up a few characters to a hidden joining header. Each part then carries 153 plain characters, per section 9.2.3.24.1 of 3GPP TS 23.040 (May 2024 edition, read October 6, 2026).

Square brackets and other symbols that count twice

A handful of plain symbols take 2 characters each: [ ] { } ~ ^ | \ and the euro sign. They keep the text plain, but they fill it faster. The tag [AHU-3] looks like 7 characters and counts as 9.

That is still a fair trade for a clear tag. Just keep one pair of brackets per alert, and never nest them.

How Welco counts your alert

Welco follows the same character rules, with brackets counted as 2. Its credit parts are slightly smaller than the network's: 152 plain characters each, or 66 with a special character. One alert never uses more than 6 credits per phone, and the credit counting rules show worked examples.

Fit any alarm into one text in 5 steps

Work from a real alert email your system sent last week. Paste it somewhere you can count characters.

  1. Find the four facts that matter

    Mark what failed, where it is, how bad it is and when it started. Everything else is a candidate for cutting. If a value helps the tech decide whether to drive in, keep it too.

  2. Lead with a short tag in brackets

    Put the equipment or site first, in square brackets, like [AHU-3] or [Lift Stn 4]. The tag shows in the lock screen preview, so the reader knows the source before opening the text. The two brackets cost 4 characters between them, so keep the name inside short.

  3. Cut labels, footers and repeats

    Remove field names, repeated dates and anything below the alarm details. Turn Alarm State: Offnormal / Unacked into HIGH or ALARM. Keep the time once, in the crew's own clock format, such as 9:47 PM or 21:47.

  4. Use plain characters only

    Swap curly quotes, degree signs, long dashes and emoji for plain letters. Write 29 C, not a degree symbol. One special character, including French letters like ê or â, can switch the whole text to a smaller 70-character limit.

  5. Set it as a rule and test it

    Turn the trim into a one-text alert rule so every future email gets the same treatment. Then run it in test mode and check the result before a real alarm goes out.

Turn long alarm emails into one clear text

Point your system at Welco and set the trim once.

7-day free trial, 15 message creditsCard required for verificationNo charge for 7 daysEmail reminder before billing

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Before and after: a building alarm cut to one text

This air handler alarm came out of a building system on a Canadian college campus at over 400 characters. The text keeps the unit, the reading, the state and the time.

Alert email from alarms@bas.example.ca, subject “Alarm Notification: AHU-3 RAT Offnormal”. Welco trims it to one text of 73 characters: “Welco: [AHU-3] Return air 29 C, HIGH at 9:47 PM. Reply STOP to opt out.”

Text received: Welco: [AHU-3] Return air 29 C, HIGH at 9:47 PM. Reply STOP to opt out.

Characters366731 credit

Animation: the alert email "Alarm Notification: AHU-3 RAT Offnormal" is trimmed into one text: "Welco: [AHU-3] Return air 29 C, HIGH at 9:47 PM. Reply STOP to opt out."

The degree sign in the email would have pushed the text to the smaller Unicode limit. Writing 29 C keeps it in plain characters.

Templates that stay under 130 characters

After the Welco: start and the opt-out line, about 130 characters are left for the alert itself. These patterns fit with room to spare, brackets included. You can copy more of them from our ready-made alert wording by system.

  • Equipment fault: [Pump 2] FAIL TO START at 3:05 AM
  • Level alarm: [Tank 1] Level LOW, 1.3 m at 6:40 PM
  • Server problem: [app-02] Disk 97% full at 1:15 AM
  • Door event: [East Door] Held open 5 min at 11:20 PM
  • Power event: [UPS-1] On battery, 18 min left at 2:02 AM

Mistakes to avoid when you shorten alerts

The most common mistake is cutting a fact the on-call person needs to act. Shorter is only better while the text still answers what, where, how bad and when.

  • Dropping the site. Pump 2 FAIL means little when you run six stations that each have a Pump 2.
  • Dropping the reading. Tank 1 LOW and Tank 1 LOW 0.3 m lead to very different nights.
  • Codes only the day shift knows. Shorten words the whole crew reads the same way, like temp or stn, and nothing else. On a bilingual crew, pick short forms that read the same in English and French.
  • Nested or doubled brackets. A tag like [[Site 4]{AHU}] spends 12 characters on punctuation alone.
  • Wording pasted from Word or Outlook. Curly quotes and long dashes ride along and switch the text to the smaller limit.
  • Links in the text. A portal link can eat half the room, and public link shorteners are one of the things that get alert texts refused.
  • Fixing one email by hand. The next alarm arrives untouched. A rule is the only trim that lasts.

Can I shorten alerts without changing my alarm system?

Yes. You change one email address in the alarm system, and Welco does the trimming. There is no software or hardware to install on site.

An alert rule decides which emails become texts, by sender, subject, words or time of day. The trim then keeps only the lines you chose. Emails a rule drops never become texts and use no credits.

The on-call person sees one short text that starts with Welco: and ends with the opt-out line. Each person joins with their own phone and replies YES before the first alert arrives.

Short alert checklist

Run each alarm type through this list once. Tick the boxes as you go.

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Frequently asked questions

How many characters can an alert text have before it splits?

A plain text holds 160 characters before the network splits it, and each network part then holds 153. Square brackets count as 2 characters each, both on the network and in Welco's count. Welco counts credits in slightly smaller parts of 152 plain characters. With a curly quote or emoji, the single-text limit drops to 70.

Should I cut the alarm time out to save space?

No, keep it. The time tells the on-call person whether the alarm is new or has been sitting for an hour. Write it once and short, like 3:05 AM or 03:05, and drop the seconds, the time zone and the repeated date.

Do I have to change the alarm email in my system?

Not always. You can leave the email as it is and set a trim rule in Welco, which keeps only the lines you choose. Changing the template at the source works too, and helps if other people read the same emails.

Why did my short alert still arrive as two texts?

Usually a hidden character. A degree sign, a pasted curly apostrophe, a French letter like ê or an emoji switches the whole text to the 70-character limit. Replace it with plain letters and test again.

Is it safe to drop the footer and disclaimer text?

Yes, for the text. The full email still exists in your system and inbox if anyone needs the details later. The text only has to get the right person moving, so it should carry the facts that drive that choice.

Are abbreviations a good idea in alarm texts for a Canadian crew?

Only the ones your whole on-call crew already uses. Stn, temp and kPa save room and nobody misreads them. Codes from a vendor manual or one person's habit slow the reader down at 3 a.m. Write out anything a new hire might not know.

What does a trimmed alert cost if it still runs long?

It uses one credit per part, and Welco stops at 6 credits per alert per phone. Each phone that gets the alert counts separately. There are no overage charges: alerts pause at the plan limit unless you hold a credit pack. Test mode shows the count before anything is sent.

Reviewed by Rakesh Patel, Founder, Welco

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