Short answer: to send bulk SMS in Sri Lanka you use an SMS gateway provider connected to the local mobile networks, register a branded sender ID (a name such as YOURBRAND), get recipient consent, and keep messages inside operator and data-protection rules. Unregistered sender IDs are at risk of being blocked on the largest networks.
Updated 25 October 2026. Operator rules change; the details below summarise public guidance from SMS industry sources, so confirm current requirements with your provider.
How bulk SMS works in Sri Lanka
Your application or dashboard sends messages to an SMS gateway over an HTTP API or SMPP connection. The gateway routes each message to the destination mobile operator, which delivers it to the handset and returns a delivery report. Numbers use the +94 country code, for example +94 7X XXX XXXX. SMS cannot be delivered to landlines.
Sender IDs: what you need to know
- Alphanumeric sender IDs show your brand name instead of a phone number, which builds trust and recognition.
- Pre-registration. Public carrier guidance says alphanumeric sender IDs must be pre-registered with the largest networks (Dialog, Hutch and Etisalat), with provisioning taking around three weeks.
- 29 July 2026 deadline. From that date, messages from unregistered sender IDs to those networks are reported as blocked. If your old campaigns used an unregistered name, register now.
- Numeric sender IDs are not reliable for delivery and are being blocked on those networks.
- Mobitel is reported to accept only OTP, OTT and transactional traffic (such as banking and payment messages) from registered IDs, so promotional messages may be blocked there.
Message length and language
- English text with the standard GSM character set fits 160 characters in a single SMS.
- Sinhala and Tamil need Unicode (UCS-2) encoding, which fits about 70 characters in a single SMS, or 67 per part when a message is split.
- One emoji or special character can switch an entire English message to Unicode, shrinking the limit and raising cost. Preview before you send.
Consent, opt-out and the PDPA
Sri Lanka's Personal Data Protection Act (Act No. 9 of 2022) requires the consent of the person to receive marketing by electronic means, and senders must tell people how to opt out, free of charge, when collecting details and with each message. Individuals can withdraw consent at any time. Penalties can reach LKR 10 million per non-compliance. Practical rules:
- Collect opt-in with a clear purpose (checkbox, form or reply keyword) and store the proof.
- Include a simple opt-out instruction in marketing messages.
- Do not send promotional SMS at night; respect do-not-disturb requests.
- Keep transactional messages (OTP, receipts, alerts) separate from promotions.
Common use cases
- OTP and login verification
- Payment, order and delivery alerts
- Appointment reminders
- Promotions and festive campaigns to opted-in customers
- Internal alerts for staff and field teams
How to choose a bulk SMS provider
- Direct operator connectivity and reliable delivery reports, not just a headline price.
- Sender ID registration support with all the major networks.
- API quality: HTTP and SMPP, clear documentation, sandbox and webhooks for delivery status.
- Transparent pricing per SMS, volume tiers and no hidden fees.
- Dashboard features: contact groups, scheduling, templates, personalisation and reports.
- Local support and compliance guidance.
Compare SMS with WhatsApp too: SMS reaches every phone with no app, while WhatsApp allows rich media, two-way chat and very low rates for utility messages. Many businesses use both; see our WhatsApp pricing in Sri Lanka.
Frequently asked questions
What is bulk SMS?
Bulk SMS is sending the same or personalised text messages to many recipients at once through an SMS gateway or platform.
Do I need to register a sender ID in Sri Lanka?
Yes for reliable delivery. Public guidance says unregistered alphanumeric sender IDs are blocked on the largest networks from 29 July 2026, and registration can take around three weeks.
Is bulk SMS legal in Sri Lanka?
Yes, with consent. The PDPA requires consent for electronic marketing and a free way to opt out.
How many characters fit in one SMS?
160 in the GSM set for English, about 70 for Sinhala or Tamil (Unicode), and 67 per part when longer messages are split.
Can I send SMS to landline numbers?
No. SMS can only be delivered to mobile numbers.
What is the cheapest way to send OTPs?
Use a transactional route with a registered sender ID. For app-based users, WhatsApp authentication messages to Sri Lanka also cost about US$0.002 each.
Related reading
- SMS gateway vs SMS API vs bulk SMS portal in Sri Lanka: which one do you need?
- WhatsApp Business API pricing in Sri Lanka from 1 October 2026: what changed
Talk to Bloomwire: explore our Bulk SMS gateway and API or contact our team for sender ID registration help and a quote.
