> For the complete documentation index, see [llms.txt](https://docs.emaillabs.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.emaillabs.io/en/sms/sms-common-settings/sender-ids/security-and-best-practises.md).

# Security and Best Practises

* **Authorization Requirements:** Using custom names requires CSO approval.
* **Character Limits:** Sender ID names must comply with character length requirements (14 digits or 11 alphanumeric characters, including spaces).
* **Prohibited Names:** Avoid using misleading names such as POLICE.
* **Two-Way Communication:** If you require the ability to receive replies, consider purchasing a 2-way communication number.