When you receive an SMS that shows GURUSM or HDFCBK instead of a phone number, that short text is the sender ID, also called the DLT header. It is one of the most important pieces of your SMS setup in India, because without a registered header you simply cannot send commercial SMS. This guide explains what a sender ID is, how to register it, the rules around it, and what good headers look like for different businesses.
What Is an SMS Sender ID or Header?
A sender ID is the alphanumeric identifier that appears as the sender of your SMS. In India it is almost always 6 characters and reflects your brand, for example a clinic might use a header derived from its name. The header is registered on the DLT platform and linked to your business entity. It gives recipients confidence that the message comes from a known, registered sender, and it lets operators apply the correct routing and filtering. Headers are central to our bulk SMS service and every campaign you run through it.
How to Register a DLT Header in India
Header registration happens on a DLT platform operated by a telecom operator (Jio, Airtel, Vi, or BSNL). The broad steps are:
- Register your entity - submit your business documents (PAN, GST, authorisation letter) to create a Principal Entity on the DLT portal.
- Apply for a header - request your 6-character header and select its type (promotional, transactional, service, or government).
- Get operator approval - the header is reviewed and, once approved, becomes usable across operators.
- Link templates - register the message templates you intend to send under that header.
This process can be confusing the first time. Guru SMS, as a TRAI-registered and DLT-compliant provider, walks you through entity registration, header approval, and template linking so you are sending compliant messages quickly. Our SMS API then lets your application send through the approved header automatically.
The Rules That Govern Headers
A few rules are worth knowing before you apply:
- Headers are typically 6 characters, alphanumeric, and tied to your brand name.
- Each header has a category (promotional, transactional, service, government) and can only be used for content matching that category.
- A promotional header cannot be used to send transactional content like OTPs, and vice versa.
- Headers must be genuinely related to your business; misleading or impersonating headers are rejected.
- Once approved, a header is reusable across all operators because DLT is shared infrastructure.
Choosing the wrong category for your header is a common mistake. If most of your traffic is OTPs and order alerts, register a transactional or service header. If you mainly run sale campaigns, register a promotional one. Many businesses register both so each kind of message uses the correct route.
Header Examples for Different Businesses
Because headers are 6 characters, brands abbreviate intelligently. Here are illustrative patterns by sector:
- Education: a coaching institute might use a header derived from its name for fee reminders and exam alerts. See our education messaging solutions.
- Healthcare: a hospital or clinic uses a brand-based header for appointment reminders and reports. Explore healthcare messaging.
- Banking and finance: NBFCs and lenders use transactional headers for EMI alerts and OTPs. See banking and finance solutions.
- Real estate: developers use promotional headers for new launch campaigns and transactional headers for site-visit confirmations.
The key point is consistency: pick a recognisable header so customers instantly know who is messaging them, which improves trust and reduces spam reports.
Why a Good Header Improves Delivery
A correctly registered header that matches the content category sails through operator filters, which is part of why Guru SMS achieves 98-99% transactional delivery across 230+ direct operator connections. A mismatched header (for example, promotional content sent under a transactional header) gets filtered or rejected, hurting your delivery rate. Getting the header right is therefore not just about compliance, it directly affects whether your message arrives.
Frequently Asked Questions
How long does header registration take?
Once your entity is registered and documents are in order, header approval typically takes a short review period on the DLT platform. A provider that assists with the process can help avoid back-and-forth that delays approval.
Can I have more than one sender ID?
Yes. Many businesses register separate headers for promotional and transactional traffic so each message type uses the correct route and category. There is no single-header limit imposed by the platform.
What documents do I need to register a header?
Generally your business PAN, GST details, and an authorisation letter are required to register the entity, after which you can apply for headers. Requirements can vary slightly by DLT operator.
Can I change my header later?
You register a new header rather than editing an existing one. If you rebrand, you apply for a fresh header reflecting the new name and link your templates to it.
Ready to start? Get a free demo or call +91-9853084604.