> For the complete documentation index, see [llms.txt](https://teamhelp.sipgate.co.uk/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://teamhelp.sipgate.co.uk/use-sipgate/telephony/how-does-hd-telephony-work.md).

# How does HD telephony work?

HD telephony enables the highest possible voice quality currently available for landline and VoIP calls and is automatically included in all sipgate plans.

**How does HD telephony sound?**\
The simple answer: Clearer, fuller, and more natural. The technical background: Unlike conventional telephony, a larger frequency spectrum of the voice is transmitted. This doesn't require any additional bandwidth from your internet connection.

**What do you need for HD telephony?**\
You don't need to make or adjust any settings in your sipgate account. If your hardware meets the requirements, you'll automatically make calls in HD. For this, you need HD-capable phones or endpoints. Specifically, this means that your VoIP phone must support the required codec (G722 and Opus) that can transmit voice in HD quality. Many phones already support these codecs, but you may need to adjust the endpoint's configuration.

**You meet all requirements but don't hear a difference?**\
A phone call always goes in two directions. If the person on the other end of the line doesn't have HD telephony, you'll automatically call in normal voice quality. However: Many telephony and device providers have already switched to HD or are working on it. Therefore, it can be assumed that HD telephony will become the absolute standard in the near future – and with sipgate, you're already perfectly set up for it.


---

# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter:

```
GET https://teamhelp.sipgate.co.uk/use-sipgate/telephony/how-does-hd-telephony-work.md?ask=<question>&goal=<endgoal>
```

`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal.

The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.