What You Need to Know

In the fast-paced world of digital marketing, SMS campaigns remain one of the most direct and effective channels to reach customers. But as you craft your next SMS announcement, there’s a technical detail that can seriously impact both your campaign cost and user experience: SMS encoding.

Let’s break down what SMS encoding is, how special characters affect it, and what that means for marketers looking to maximize ROI while keeping messages engaging.

What Is SMS Encoding?

When you send an SMS, the message isn’t just passed along in plain text. It’s encoded, or translated into a format that mobile networks can deliver. The type of encoding determines:

• Which characters you can use

• How many characters fit in a single SMS

• Whether your message is sent as one or multiple SMS segments

The two most common encoding types are GSM-7 and Unicode (UCS-2).

GSM-7: The Default and Most Efficient

GSM-7 is the standard character set for most SMS messages. It includes:

• Basic Latin letters (A–Z, a–z)

• Numbers (0–9)

• Common punctuation and symbols (e.g., !, @, #)

Character Limit:

• 160 characters per message

• If the message is split (concatenated), each segment holds 153 characters (to allow for headers).

Why Marketers Like GSM-7:

• Efficient — allows longer messages.

• Lower cost — fewer message segments needed.

• Universally supported — works on almost all mobile phones.

Unicode (UCS-2): For Non-Standard or Special Characters

Unicode is required when your message includes:

• Emojis

• Accented characters (é, ñ, ü)

• Non-Latin alphabets (e.g., Chinese, Arabic, Cyrillic)

Character Limit:

• 70 characters per message

• Concatenated messages are 67 characters per segment.

Why Marketers Should Be Cautious:

• Messages are shorter.

• Costs can increase if the message gets split into multiple segments.

• Can be essential for localization or personalization.

Common Characters That Trigger Unicode Encoding

You might think you’re sticking to standard text, but a single special character can convert your entire message into Unicode. Here are a few common culprits:

• Emojis

• Curly quotes (“ ”)

• Accented characters (e.g., naïve, fiancé)

• Symbols not in GSM-7 (€, ©, ™)

Tip: Use online SMS encoding checkers to test your messages before sending.

Why This Matters for Your SMS Marketing Strategy

1. Campaign Cost Management
   Using special characters may double or triple your costs if your message breaks into multiple segments. Always calculate how many segments your message will use.

2. Message Delivery and Timing
   Multipart messages can lead to delays or out-of-order delivery, which could hurt time-sensitive campaigns like flash sales or limited-time offers.

3. Brand Tone and Engagement
   Emojis and accents can boost engagement and make messages feel personal and on-brand. Just make sure the trade-off in message length and cost is worth it.

Best Practices for SMS Encoding in Marketing

• Stick to GSM-7 whenever possible for efficiency.
• Test messages with different encodings before launching a campaign.
• Use emojis sparingly — prioritize clarity over cleverness.
• Avoid special punctuation (like curly quotes copied from Word or Google Docs).
• Segment by region or language if you’re localizing and need Unicode for non-Latin alphabets.
• Preview message length and segment count using your SMS platform or a character counter tool.

Conclusion: Smart Messaging Starts with Smart Encoding

Understanding the difference between GSM-7 and Unicode can help you create SMS campaigns that are both cost-effective and impactful. As you build your next campaign, take a moment to consider how every character affects your bottom line.

Keep your messages clear, concise, and encoding-aware, and you’ll be well on your way to higher engagement and a better ROI.