# Set up a SIP Phone

Once you have a SIP extension in Cloud Voice, you can point a physical SIP phone at it. This page walks through collecting the registration details from the PBX and entering them on the phone.

:::note[What "registering" means]
SIP (Session Initiation Protocol) is the signaling language phones use to set up calls. When a phone "registers", it tells the PBX (Private Branch Exchange, the system that routes your calls) which extension it is and how to reach it. Until the phone registers, it cannot make or receive calls on that extension.
:::

## Before you start

Make sure you have already [created a SIP extension](/pbx/administrator-guide/create-a-sip-extension/). The phone registers against that extension, so it must exist first.

## Collect the registration details

Most SIP phones ask for the same set of values to connect to Cloud Voice. Gather all of the following before you touch the phone:

- **PBX domain name**: the address the phone registers to.
- **SIP registration port**: Cloud Voice uses `5060` by default.
- **Transport protocol**: find it under **Extension and Trunk > Extension > Advanced > Transport**. This is how the phone and the PBX talk (for example UDP, TCP, or TLS).
- **Extension credentials**: open **Extension and Trunk > Extension > User** and note the:
  - Extension number
  - Registration name
  - Registration password
  - Caller ID name (the name shown to the people this extension calls)

:::tip[Registration name is not always the extension number]
The **registration name** (sometimes called the SIP user ID or auth name) can be different from the extension number. Copy each value exactly as it appears in the portal, and treat the registration password as case-sensitive. A single mistyped character stops the phone from registering.
:::

## Register the phone

Sign in to the phone's own web interface, enter the values you collected above, and save. The phone then attempts to register with Cloud Voice using those credentials.

:::caution[Transport protocol must match on both ends]
The transport protocol you set on the phone has to match the **Transport** value on the extension in the PBX. If one side is set to UDP and the other to TLS, the phone will not register even when every other field is correct.
:::

## Confirm the registration

Verify that the extension came online using either method:

- On the phone's web interface, check that it reports the extension as registered.
- In the Cloud Voice portal, go to **Extension and Trunk > Extension** and look at the **Online Status** column. A registered SIP phone shows the ![SIP endpoint online](/images/pbx/SIP.png) icon.

:::note[Where to look in the portal]
The **Online Status** column sits on the main **Extension** list. The SIP icon appearing there is the PBX confirming it has accepted the phone's registration, so it is the most reliable place to check.
:::

When the extension registers successfully, the phone is ready to go and users can start making and receiving calls.