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SMS segments explained: the 160 character limit for Canadian alerts

A single text holds up to 160 plain characters. Longer texts are split into parts called segments, and each part holds 153 characters. One emoji, curly quote, symbol like ° or many French accented letters drop those limits to 70 and 67. Welco counts message credits in a similar way, so the shorter and plainer the alert, the fewer it uses.

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The problem

One alarm, 3 segments

  • The whole job email goes out as a text
  • About 380 characters with the header and footer
  • 3 segments, so 3 credits for one alarm

The fix

One alarm, 1 segment

  • Only the job, the result and the time
  • About 100 plain characters
  • 1 segment, so 1 credit
Illustration: the problem, one alarm, 3 segments, next to the fix, one alarm, 1 segment.
  • Plain text: 160 characters in one segment, 153 per part when it runs longer.
  • One emoji, curly quote, degree sign or a letter like ê switches the whole text to 70 and 67.
  • Spaces, line breaks, the Welco: start and the STOP line all count.
  • For how Welco bills, see What is a message credit?

What is an SMS segment?

An SMS segment is one block of a text message, the most a network carries in a single piece. A short text fits in one segment. A long text is cut into several segments, sent separately and joined back together on the phone. Several of our guides for alert texts build on this idea.

The reader sees one message. The network, and your bill, see each part. That is why a long alert email can cost several times more than a short one. On the lock screen, both look like a single text.

How many characters fit in each SMS segment?

The limit depends on which alphabet the text uses. Plain text uses GSM-7, the basic set of letters, numbers and symbols every phone shares. Anything outside that set forces Unicode, a much bigger alphabet that takes more room per character. Both limits come from 3GPP TS 23.038, the network alphabet standard (May 2024 edition, read October 6, 2026).

Longer texts lose a few characters per part because each part carries a small hidden header that tells the phone how to rejoin them.

Plain text (GSM-7)

Text fits in one segment
Up to 160 characters
Each part of a longer text
153 characters

Unicode (emoji, curly quotes, many symbols)

Text fits in one segment
Up to 70 characters
Each part of a longer text
67 characters

Sources: 3GPP TS 23.038 V18.0.0, alphabets (ETSI) (read October 6, 2026); 3GPP TS 23.040 V18.0.0, section 9.2.3.24.1 (ETSI) (read October 6, 2026)

What happens when a text goes over 160 characters?

The network cuts it into numbered parts, sends each one on its own and lets the phone stitch them back together. The joining header takes 7 characters from every part, which is why each part holds 153 and not 160.

The rule sits in section 9.2.3.24.1 of 3GPP TS 23.040, the SMS standard (May 2024 edition, read October 6, 2026). The same section allows up to 255 parts in one long message. It also says a two-character symbol is never split across two parts.

Parts can arrive out of order, and the phone waits for all of them before it shows the message. On a weak signal, a 4-part alert can show up later than a 1-part alert sent at the same moment.

Why does one emoji make a text cost more?

One character outside GSM-7 switches the whole text to Unicode, not just that character. A 120-character alert fits in one plain segment. Add one emoji and the same alert needs 2 segments.

Alert systems rarely send emoji, but they often send other characters that do the same thing. These are the usual suspects in alarm emails.

  • The degree sign (°). Temperature and freezer alarms in Celsius use it all the time, and it isn't in GSM-7.
  • Curly quotes and long dashes. Outlook and Word turn straight quotes into curly ones when an email is forwarded.
  • Many accented letters. This matters for bilingual and Quebec sites. A few, like é and è, are in GSM-7, but common French letters like ê, â and ô are not.
  • Symbols like ±, µ and the bullet •. These show up in lab, process and report emails.

Characters that count twice in plain text

A few symbols are in GSM-7 but take 2 spaces each. These are [ ] { } ~ ^ | \ and the euro sign €. They don't switch the text to Unicode, but a line full of them fills a segment faster. The standard calls this the extension table, and each one is sent as an escape code plus the symbol.

Count the characters in a real alert

Here is a freezer alarm text: Welco: [Cold Room 1] Temp 6.8°C high alarm at 2:05 AM. Reply STOP to opt out. It has 77 characters, counting every space, the Welco: start and the STOP line.

The ° sign forces Unicode, so the limit drops to 70. At 77 characters, this alert needs 2 segments.

Now change 6.8°C to 6.8 C in the logger's alert template. The text is plain again, with a limit of 160. The two brackets count twice, so it uses 79 of the 160 spaces and fits in 1 segment.

How do Welco message credits relate to SMS segments?

Welco credits follow the same idea as segments, with slightly smaller parts. A whole alert of up to 160 plain characters, or 70 with a special character, uses 1 credit per phone.

Past that, Welco counts parts of 152 plain characters, or 66 with a special character. That is a little under the network's 153 and 67. So a text right at a part boundary can use one credit more than its segment count. Square brackets and the other double symbols count as 2 in Welco's count too.

Two limits protect you on long alerts. One alert never uses more than 6 credits per phone, and there are no overage charges. The rules for counting message credits walk through more examples.

Keep an alert to one SMS segment in 5 steps

Do this once per alert template. The savings repeat on every alarm after that.

  1. Count the alert as it goes out today

    Paste a recent alert into any character counter, including the Welco: start and the Reply STOP to opt out. line. Note the length and whether it has any special characters.

  2. Remove the characters that force Unicode

    Change ° to a plain C, curly quotes to straight ones, and bullets to dashes or new lines. Make these changes in the alarm system's template, so every future alert is plain.

  3. Cut the parts nobody reads on a phone

    Headers, footers, legal notes and repeated dates fill segments fast. One-text alerts keep the part that matters and drop the rest.

  4. Put the key facts first

    Lead with the site, the problem and the time. If the text ever runs long, the phone shows the important part on the lock screen first. For wording tips, see how to write alerts that fit one text.

  5. Check it in test mode

    Run a sample alert through test mode. It shows the text Welco would send without sending it or using credits.

Trim your alerts to one segment

Point your alert email at Welco and keep each alarm to one short text.

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

Send one-segment alertsBook a demo

A long batch job email trimmed to 1 segment

A credit union's day-end job scheduler sends this email when a run finishes with errors. Sent whole, with the Welco: start and the STOP line, it is about 380 characters. That is 3 segments.

Alert email from scheduler@ops.example.ca, subject “Warning: DAYEND for BK104 completed with errors”. Welco trims it to one text of 102 characters: “Welco: [BK104] Day-end batch finished with errors at 11:48 PM. Step 9 failed. Reply STOP to opt out.”

Text received: Welco: [BK104] Day-end batch finished with errors at 11:48 PM. Step 9 failed. Reply STOP to opt out.

Characters3981021 credit

Animation: the alert email "Warning: DAYEND for BK104 completed with errors" is trimmed into one text: "Welco: [BK104] Day-end batch finished with errors at 11:48 PM. Step 9 failed. Reply STOP to opt out."

The trimmed text is 100 characters, or 102 with the brackets counted twice. It fits in 1 segment, and the full email still lands in the team's inbox.

Mistakes to avoid when counting segments

Most surprise multi-part alerts come from counting the wrong thing. These are the slips we see most often.

  • Counting only the alarm line. The Welco: start, the STOP line, spaces and line breaks all count.
  • Trusting any online counter. Many count [ as one character and miss that ° forces Unicode.
  • Looking for emoji only. A degree sign, a curly apostrophe or a bullet does the same damage.
  • Judging by the phone screen. A joined message looks like one text even when it was billed as three.
  • Fixing the forwarded copy. If a mail rule adds a banner after you trim, the text grows again. Test the real path end to end.
  • Trimming in one system only. Each alarm source has its own template, so check them one by one.

Before you save an alert template

A quick check that keeps each alarm to one segment.

0 of 7 done

Frequently asked questions

Why does my 100-character alert need two segments?

It almost certainly contains a character outside the plain GSM-7 alphabet. That switches the whole text to Unicode, where one segment holds only 70 characters. Common causes in Canadian alerts are the degree sign, a curly quote from Outlook, a French accent like ê or a bullet. Remove it in the alarm template and the alert fits one segment again.

Do spaces and line breaks count toward the 160 characters?

Yes. Every space and every line break counts as one character, the same as a letter. Alert emails often carry blank lines and long runs of spaces between fields, and those add up fast. One-text alerts drop the extra spacing along with headers and footers, so more of the segment goes to facts.

Is the Welco: prefix counted in the segment on Canadian phones too?

Yes, on every phone. The text starts with Welco: and ends with Reply STOP to opt out, and both count toward the length. Together they take about 30 characters. That leaves roughly 130 plain characters in one segment for the alarm itself, which is plenty for the site, the problem and the time.

Does the degree sign in a temperature alarm cost extra?

It can. The degree sign isn't in the plain GSM-7 alphabet, so it switches the text to Unicode with a 70-character limit. A Celsius freezer alarm that would fit in one plain segment may need two. Change ° to a plain C in the logger's alert template to avoid it.

Will the on-call phone show a multi-part alert as one message?

Almost always. Modern phones join the segments back together and show one message. The parts are still billed one by one, so the cost is the same either way. Keeping the important facts first means the lock screen preview shows what matters, even on a long alert.

Is there a maximum length for one long text message?

The SMS standard allows up to 255 parts, which is far more than any alert needs. Phones and networks may set lower limits of their own. Welco caps each alert at 6 credits per phone, however long the email is. A trim rule is still the better fix, because nobody reads a 6-part alert at night.

Do Welco credits always match the carrier's segment count?

Almost always, but not exactly. Welco counts long alerts in parts of 152 plain characters, a little under the network's 153. So a text that just fills 2 network parts can use 3 credits. Test mode shows the credit count before anything is sent.

Reviewed by Rakesh Patel, Founder, Welco

Pay for one segment, not three

Send each alarm as one short, plain text that the on-call person can read at a glance.

Send one-segment alertsBook a demo

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