---
title: What are DLT variable tags, and which one should I use?
description: "Under TRAI's direction of 18 November 2025, every variable in a DLT content template must be **tagged with the type of data it will hold**, instead of using the generic `{#var#}`. Operators check each value you send against its tag,…"
url: "https://www.smsgatewaycenter.com/blog/kb/what-are-dlt-variable-tags-and-which-one-should-i-use/"
updated: "2026-09-18"
category: Bulk SMS / DLT / Variable Tagging
---

# What are DLT variable tags, and which one should I use?

Under TRAI's direction of 18 November 2025, every variable in a DLT content template must be **tagged with the type of data it will hold**, instead of using the generic `{#var#}`. Operators check each value you send against its tag, and messages that fail the check are rejected once enforcement is fully on.

## The six tags

| Tag | Use it for | Rules |
| --- | --- | --- |
| `{#numeric#}` | OTPs, amounts, account or order numbers made only of digits | Digits 0–9 only; up to 40 characters |
| `{#alphanumeric#}` | Names, reference IDs, ticket numbers | Letters and numbers; up to 40 characters; must not contain a link |
| `{#url#}` | Website and landing-page links | Up to 120 characters; must match a whitelisted URL CTA |
| `{#urlott#}` | App download and OTT links, such as WhatsApp links | Up to 120 characters; must match a CTA registered under OTT or APK |
| `{#cbn#}` | Callback numbers | 3–14 digits; must match a whitelisted Number CTA; keep "+91" in the fixed text |
| `{#email#}` | Email addresses | A valid email format; up to 40 characters |

## Example

Before: `Dear {#var#}, your OTP is {#var#}. Track at {#var#}`

After: `Dear {#alphanumeric#}, your OTP is {#numeric#}. Track at {#url#}`

## Tips

- Pick the **narrowest** tag that fits. For example, use `{#numeric#}` for an OTP, not `{#alphanumeric#}`.
- Make sure the values your system sends match the tag: no spaces or symbols in `{#numeric#}`, and no links in `{#alphanumeric#}`.
- Only `{#alphanumeric#}` may appear back to back without fixed text in between.

**Official source:** [TRAI Direction on variable tagging, 18 Nov 2025](https://www.trai.gov.in/sites/default/files/2025-11/Directions_18112025_0.PDF).

See also our blog post: [Mandatory variable tagging for DLT SMS templates](https://www.smsgatewaycenter.com/blog/trai-dlt-mandatory-variable-tagging-sms-templates/).

### More Related Articles

- [How do I update my existing DLT templates to use variable tags?](https://www.smsgatewaycenter.com/blog/kb/how-do-i-update-my-existing-dlt-templates-to-use-variable-tags/)

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