---
title: What does FORMAT_ISSUE (Format Issue in MSISDN/Subscriber/Address) mean?
description: "There was a **format problem with the number (MSISDN), subscriber id, or address** - for example invalid characters, wrong length, or incorrect structure. The message was not sent or was rejected. **What you can do:** Check that recipient numbers and any subscriber/address…"
url: "https://www.smsgatewaycenter.com/blog/kb/what-does-format_issue-format-issue-in-msisdn-subscriber-address-mean/"
updated: "2026-05-25"
category: "Bulk SMS / Errors & Error Codes"
---

# What does FORMAT_ISSUE (Format Issue in MSISDN/Subscriber/Address) mean?

There was a **format problem with the number (MSISDN), subscriber id, or address** - for example invalid characters, wrong length, or incorrect structure. The message was not sent or was rejected.

**What you can do:** Check that recipient numbers and any subscriber/address fields use the correct format (e.g. country code, digits only, no extra characters). Clean your list and fix the format.

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