What is DLT registration and why is it needed for SMS in India?

DLT (Distributed Ledger Technology) is TRAI-mandated for all commercial SMS in India. Businesses must register entity, sender IDs, and templates. Unregistered SMS are blocked by operators.

Free SMS Character Counter & Cost Calculator

Q: What is the difference between GSM 7-bit and Unicode encoding?

GSM 7-bit supports Latin letters, digits, and common symbols with 160 characters per segment. Unicode supports all scripts including Hindi and emojis but only allows 70 characters per segment.

Q: Why is the limit 153 not 160 for multi-part SMS?

Multi-part SMS segments include a 7-byte User Data Header (UDH) for reassembly, reducing capacity from 160 to 153 for GSM and from 70 to 67 for Unicode.

Q: What is the cost per SMS in India?

Bulk SMS pricing in India ranges from Rs 0.10 to Rs 0.25 per SMS depending on volume, route type, and provider.

Instantly count SMS characters, calculate message segments, detect GSM vs Unicode encoding, and estimate bulk SMS costs for India. DLT compliant.

SMS Character Counter Tool

Type or paste your SMS message below. Character count, segments, encoding, and cost update in real time.

Characters

0 / 160

SMS Segments

Encoding

GSM 7-bit

Chars / Segment

160

Est. Cost (₹0.15/SMS)

₹0.00

0 characters usedLimit: 160

Unicode Detected! Your message contains Unicode characters (Hindi/emoji). This reduces the maximum from 160 to 70 characters per segment. Non-GSM characters found:

Bulk SMS Cost Calculator

Number of Recipients

Cost per SMS (₹)

Total SMS

Estimated Cost

₹0.00

GSM 7-Bit Character Reference

Understanding which characters are GSM-compatible helps you keep SMS costs low by staying within the 160-character single-segment limit.

Standard GSM 7-Bit Characters (count as 1)

Category	Characters
Letters	A–Z, a–z
Digits	0–9
Punctuation	. , ; : ! ? " ' ( ) - / @ & # * + = < > %
Symbols	$ £ ¥ ¤ § ¿ ¡ _ ‎Space
Greek	Δ Φ Γ Λ Ω Π Ψ Σ Θ Ξ
Accented	è é ù ì ò Å å Ø ø Ç Ä Ö Ñ Ü ä ö ñ ü à
Whitespace	Line feed (LF), Carriage return (CR), Space

Extended GSM Characters (count as 2)

These characters use an escape sequence and consume 2 character slots in your SMS:

^{}[]~|€\

Characters That Trigger Unicode (70 chars/segment)

If your message contains any of these, the entire SMS switches to Unicode encoding:

Hindi (अआइ...)Emojis (😀😍🚀)Arabic (ابت)Chinese (中文)Smart quotes (“ ” ‘ ’)Em dash (—)Bullet (•)© ® ™

SMS Best Practices

Follow these tips to optimize your bulk SMS campaigns for maximum delivery and minimum cost.

Keep Under 160 Characters

A single SMS segment costs one credit. Messages over 160 characters split into multiple segments, doubling or tripling your cost. Use our SMS character counter to stay within the limit.

Avoid Unicode Unless Needed

Unicode (Hindi, emoji) reduces capacity from 160 to 70 characters per segment. Use English GSM characters for promotional SMS. Reserve Unicode for Hindi-language messages where readability matters.

Register Sender ID with DLT

TRAI mandates DLT registration for all commercial SMS in India. Register your sender ID (header), SMS templates, and entity details on your operator’s DLT portal before sending.

Use URL Shorteners for Links

Long URLs consume precious characters. Use branded short links to save space and track click-through rates. Ensure short links are whitelisted on your DLT template.

Test Before Bulk Send

Always run your message through an SMS length calculator before sending to thousands. Check for hidden Unicode characters, smart quotes from copy-paste, and segment count.

DLT Compliance for India

Every SMS template must be pre-approved on the DLT platform. Variable fields use placeholders like {#var#}. Non-compliant messages get blocked by telecom operators.

Frequently Asked Questions

Common questions about SMS character counting, segments, and bulk SMS in India.

What is an SMS segment and how does it affect cost?

An SMS segment is a single message unit. Standard GSM messages allow 160 characters per segment. If your message exceeds 160 characters, it splits into multiple segments. Each segment counts as one SMS for billing. For example, a 170-character GSM message uses 2 segments (and costs 2x), because multi-part GSM messages use 153 characters per segment due to concatenation headers.

What is the difference between GSM 7-bit and Unicode encoding?

GSM 7-bit encoding supports 128 standard characters (Latin letters, digits, common symbols) and allows 160 characters per SMS segment. Unicode (UCS-2) supports all world scripts including Hindi, Arabic, Chinese, and emojis but only allows 70 characters per segment. If even one character in your message requires Unicode, the entire message switches to Unicode encoding, reducing capacity significantly.

Why is the limit 153 (not 160) for multi-part SMS?

When an SMS is split into multiple segments, each segment needs a User Data Header (UDH) of 7 bytes to help the receiving phone reassemble the parts in correct order. This header reduces the available space from 160 to 153 characters per segment for GSM, and from 70 to 67 for Unicode messages. The SMS segments calculator accounts for this automatically.

What is DLT registration and why do I need it for SMS in India?

DLT (Distributed Ledger Technology) is a TRAI-mandated platform for regulating commercial SMS in India. All businesses must register their entity, sender IDs (headers), and message templates on the DLT portal of their telecom operator (Jio, Airtel, Vi, BSNL). Unregistered SMS are blocked by operators. This was implemented to curb spam and protect consumers.

What is the cost per SMS in India for bulk messaging?

Bulk SMS pricing in India typically ranges from ₹0.10 to ₹0.25 per SMS depending on volume, route (transactional vs promotional), and provider. Transactional SMS (OTPs, alerts) cost slightly more but have higher priority. Our bulk SMS calculator defaults to ₹0.15/SMS. Contact us for custom pricing based on your volume requirements.

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