SMS Limitations that Every Business Should Know

SMS Limitations Every Business Should Know

SMS works on almost any phone. No app, no internet, and people tend to read texts fast. That’s why businesses keep using it for reminders, alerts and promotions.

But it has limits, and most of them show up on your invoice or delivery report before you notice them in your planning. A message that looks like one text in your editor can bill as three. A campaign can say “sent” while a chunk of it never lands. Here are the SMS limitations that matter most and what you can do about each.

The quick version

1. The character limit (and the encoding trap)

One SMS holds 160 characters in standard GSM-7 encoding. Go over, and it splits into 153-character segments, each billed on its own.

Here’s the part teams usually learn the hard way. Add a single emoji, a curly quote pasted from a doc, or one non-Latin character, and the whole message flips to Unicode. That holds just 70 characters, or 67 per segment once split. One smiley can cut your limit by more than half.

Now count what’s really in your message: a link (often 20 to 30 characters), merge fields like name and date, your “Reply STOP to opt out” line, and your business name. A draft that reads 140 characters in your editor can hit 190 once the fields fill in. That’s two segments. Across a list of 20,000 people, you’ve just paid for 20,000 extra messages.

What to do: Test with your longest realistic name and date, not “Sam” and “Friday.” Skip the emoji unless it earns its cost. If you write in Hindi, Arabic or any non-Latin script, plan around 70 characters from day one.

2. SMS is text only

Plain SMS carries words. No images, no video, no PDFs, no buttons. If your product sells on how it looks (retail, real estate, healthcare), that hurts.

MMS can carry media, but it costs more, has size limits and behaves differently across carriers. Plenty of messaging tools don’t support it at all. WhatsApp Business is the usual answer for images, documents and buttons, though your customer has to use WhatsApp, and business-initiated conversations carry their own charges.

3. Compliance isn’t optional

SMS is not a free-for-all. Depending on where your customers are, you might deal with several rule sets at once:

• TCPA (US): proper consent before marketing texts, with a record of it.
• 10DLC (US): business texting over standard numbers needs brand and campaign registration.
• TRAI / DLT (India): senders and templates must be registered, and a message that doesn’t match its approved template can be rejected.
• GDPR (EU): strict consent and data-handling rules.
• Quiet hours: CTIA guidance says no texts outside 8 AM to 9 PM local time, and some US states, Texas among them, add their own restrictions. Check the current rules for every state you send to before scheduling anything.

This isn’t legal advice, but the habit is simple: get consent, keep proof, honor STOP immediately, register before you send, and don’t text at odd hours. Skip those and you don’t just risk a fine. You get blocked messages and a bruised sender reputation.

4. Delivery is never guaranteed

Email gives you bounces and open data. SMS leaves you at the mercy of networks you don’t control.

Messages fail for all kinds of reasons: carrier filtering (especially for unregistered senders), dead or invalid numbers, landlines, congestion during big sends, even blocked sender IDs in some countries. Public link shorteners like Bitly are a classic trigger too. We went deeper on that in our carrier filtering post.

Delivery receipts help, but they’re inconsistent across carriers, and “delivered” doesn’t always mean it reached the handset. Some messages just vanish.

Speed is another catch. Carriers cap how fast a number can send, and in the US your registration tier affects daily volume. Blast 50,000 texts at once and some will sit in a queue for hours. Fine for a newsletter. Not fine for a flash sale that ends at noon.

What to do: Don’t judge a campaign by “sent.” Watch your delivery rate over time, read the failure codes, and chase sudden drops fast. Stagger big sends when timing matters.

5. No threading, no memory

Standard SMS has no conversation history or context. Each text arrives alone. For support, that gets messy quickly: replies pile into a shared inbox, two people answer the same customer, and nobody can see what was said last week.

A CRM fixes this. If every message sits on the Lead, Contact or Case it belongs to, your team sees the whole story without digging through someone’s phone.

6. SMS isn’t private

SMS isn’t end-to-end encrypted. Messages pass through carriers and can be stored along the way. That’s fine for an appointment reminder. It’s not fine for medical details, account numbers or passwords.

The rule of thumb: send a nudge, not the secret. “Your results are ready, log in to view them” beats putting the results in the text. And since SMS shows only a number or sender ID, with no verified business profile like WhatsApp has, customers are rightly wary of unexpected texts. Use a consistent sender, name your business in the first line, and steer clear of anything that smells like phishing.

When SMS is still the right call

None of this makes SMS a bad channel. For short, time-sensitive messages it’s hard to beat: appointment reminders, delivery updates, payment notices, “reply Y to confirm.” It reaches people who don’t use any particular app.

Trouble starts when SMS gets asked to do jobs it wasn’t built for, like long content, rich visuals or sensitive data. Use it for what it’s good at and pick another channel for the rest.

How MessageBlink helps with these limits

MessageBlink is a Salesforce-native app for SMS and WhatsApp, listed on the AppExchange. It doesn’t change what SMS is. It just makes the limits easier to live with if your team already works in Salesforce:

• Messages live on the record. Sent and received texts are logged against the Lead, Contact, Case or custom object.
• SMS and WhatsApp together. Need an image or a button? Use WhatsApp without switching tools.
• STOP replies recorded, so those contacts aren’t messaged again.
• Delivery status on the record, so failures are easier to spot.

Sender and number registration (10DLC, DLT) is set up with your SMS provider, so confirm that part with them. And once more: no MMS.