# SIP connectivity reference

Use this reference to look up the network, signaling, media, authentication,
encryption, codec, DTMF, monitoring, and firewall specifications for inbound
SIP trunks. For an explanation of how these components work together, see
[SIP connectivity](sip-connectivity.html). For destination construction,
registration behavior, and routing-method selection, see [SIP routing
methods](sip-routing-methods.html).

## Signaling

### Static Endpoint signaling addresses

For calls delivered through a **Static Endpoint** trunk, DIDWW originates SIP
signaling from the following addresses.

| Location | IPv4 address | IPv6 address |
| --- | --- | --- |
| New York | `46.19.209.14` | `2a01:ad00:1:14::14` |
| Frankfurt | `46.19.210.14` | `2a01:ad00:2:14::14` |
| Los Angeles | `46.19.212.14` | `2a01:ad00:4:14::14` |
| Miami | `46.19.213.14` | `2a01:ad00:5:14::14` |
| Singapore | `46.19.214.14` | `2a01:ad00:6:14::14` |
| Hong Kong | `46.19.215.14` | `2a01:ad00:7:14::14` |
| Amsterdam | `185.238.173.14` | `2a01:ad00:8:14::14` |

### Dynamic Registration registrar addresses

When using **Dynamic Registration**, configure the customer system to
register to one of the following hostnames. Use `sip.didww.com` for
automatic DNS-based load balancing between locations. Use
`nyc.sip.didww.com` to select New York or `ams.sip.didww.com` to select
Amsterdam.

| **Hostname** | **IPv4 address** | **IPv6 address** |
| --- | --- | --- |
| `sip.didww.com` | `46.19.209.49` | `2a01:ad00:1:1::49` |
| `185.238.173.49` | `2a01:ad00:8:1::49` |
| `nyc.sip.didww.com` | `46.19.209.49` | `2a01:ad00:1:1::49` |
| `ams.sip.didww.com` | `185.238.173.49` | `2a01:ad00:8:1::49` |

### Network protocol values

The following IP protocol values are available for a Static Endpoint trunk.

| Value | Behavior |
| --- | --- |
| IPv4 only | Uses IPv4 exclusively. |
| IPv6 only | Uses IPv6 exclusively. |
| Any | Allows either IPv4 or IPv6. This is the default value. |
| Prefer IPv4 over IPv6 | Uses IPv4 when available and falls back to IPv6. |
| Prefer IPv6 over IPv4 | Uses IPv6 when available and falls back to IPv4. |

### Transport protocol values

| Value | Behavior |
| --- | --- |
| UDP | Uses User Datagram Protocol for SIP signaling. This is the default value. |
| TCP | Uses Transmission Control Protocol for SIP signaling. |
| TLS | Uses Transport Layer Security to encrypt SIP signaling. |

### Signaling source ports

DIDWW originates inbound SIP signaling from the following source ports for
both routing methods.

| Transport | Source port | Firewall requirement |
| --- | --- | --- |
| UDP | `5060` | Accept UDP signaling from the applicable DIDWW signaling addresses. |
| TCP or TLS | `5070-65535` | Accept TCP or TLS signaling from the applicable DIDWW signaling addresses across this dynamic source-port range. |

The destination port for Static Endpoint delivery is configured on the
trunk. When the **Port** field is empty, DIDWW uses DNS SRV. See [DNS
SRV failover](call-handling-and-delivery/service-failover-and-load-balancing.html#inbound-sip-dns-srv-failover).

### Authentication

| Routing method | Mechanism | Behavior |
| --- | --- | --- |
| Static Endpoint | Optional SIP digest authorization | **Enable Authorization** makes DIDWW authenticate its `INVITE` requests with the configured **Auth User** and **Auth Password**. **From User** and **From Domain** can override the corresponding `From` header components. See [Authorization](sip-trunk-settings-reference.html#inbound-sip-trunks-settings-authorization). |
| Dynamic Registration | SIP digest registration | The customer system registers with the generated **Username** and **Password**. The generated credentials and registrar hostnames are read-only after creation. See [View SIP registration credentials](how-to-guides/view-sip-registration-credentials.html). |

## Media

### RTP source subnets

DIDWW sends RTP from the following subnets.

| **IP version** | **Source subnet** |
| --- | --- |
| IPv4 | `46.19.208.0/21` |
| `185.238.172.0/22` |
| IPv6 | `2a01:ad00:1:2::/64` |
| `2a01:ad00:1:14::/64` |
| `2a01:ad00:2:1::/64` |
| `2a01:ad00:2:14::/64` |
| `2a01:ad00:4::/64` |
| `2a01:ad00:4:14::/64` |
| `2a01:ad00:5::/64` |
| `2a01:ad00:5:14::/64` |
| `2a01:ad00:6::/64` |
| `2a01:ad00:6:14::/64` |
| `2a01:ad00:7:1::/64` |
| `2a01:ad00:7:14::/64` |
| `2a01:ad00:8:1::/64` |
| `2a01:ad00:8:14::/64` |

### RTP and RTCP ports

| Protocol | Port | Behavior |
| --- | --- | --- |
| RTP | `1024-65535` | DIDWW sends RTP from this port range. |
| RTCP | RTP port + 1 | DIDWW sends and receives RTCP on the port immediately after the RTP port, as recommended by [**RFC 3550**](https://datatracker.ietf.org/doc/html/rfc3550.html). DIDWW can also receive RTCP on the RTP port when RTCP conflict avoidance payload types 72-76 are used. |

### Supported codecs

| **Option** | **Type** | **Description** |
| --- | --- | --- |
| PCMU | Audio codec | G.711 μ-law audio codec. |
| PCMA | Audio codec | G.711 A-law audio codec. |
| G729 | Audio codec | G.729 audio codec. |
| G723 | Audio codec | G.723.1 audio codec. |
| L16 | Audio codec | Linear PCM audio codec. |
| G726-16 | Audio codec | G.726 audio codec at the selected bit rate. |
| G726-24 |
| G726-32 |
| G726-40 |
| G721 | Audio codec | G.721 audio codec. |
| GSM | Audio codec | GSM Full Rate audio codec. |
| Speex | Audio codec | Speex audio codec. |
| telephone-event | RTP event payload | RTP payload used for [**RFC 2833**](https://datatracker.ietf.org/doc/html/rfc2833.html) DTMF events. |

By default, **PCMU**, **PCMA**, **G729**, **G723**, and **telephone-event** are
selected on a new inbound SIP trunk. Codec order determines preference. See
[Media & DTMF](sip-trunk-settings-reference.html#inbound-sip-trunks-settings-media-dtmf) for the trunk
configuration fields.

### DTMF transport methods

| **Method** | **Content type or payload** | **Support** |
| --- | --- | --- |
| [**RFC 2833**](https://datatracker.ietf.org/doc/html/rfc2833.html) | `telephone-event` RTP payload | Supported for sending and receiving. This is the default send and receive method. |
| [SIP INFO](https://datatracker.ietf.org/doc/html/rfc6086) | [application/dtmf-relay](https://datatracker.ietf.org/doc/html/draft-kaplan-dispatch-info-dtmf-package-00) | Supported for sending and receiving. |
| [application/dtmf](https://www.rfc-editor.org/rfc/rfc4504.html#section-3.9) |

The send and receive methods are configured independently. See [DTMF
Send Mode values](sip-trunk-settings-reference.html#inbound-sip-dtmf-send-values) and [DTMF Receive Mode
values](sip-trunk-settings-reference.html#inbound-sip-dtmf-receive-values).

## Encryption

| **Layer** | **Mechanism** | **Specification** |
| --- | --- | --- |
| SIP signaling | TLS | Encrypts SIP signaling between DIDWW and the customer SIP endpoint. |
| RTP media | SRTP SDES | Encrypts RTP and negotiates keys with SDP Security Descriptions. |
| SRTP DTLS | Encrypts RTP and negotiates keys with Datagram Transport Layer Security. See [**RFC 5764**](https://datatracker.ietf.org/doc/html/rfc5764.html). |
| SRTP ZRTP | Encrypts RTP and negotiates keys with ZRTP. |

Note

Encryption applies only to the DIDWW-to-customer call leg. It is not
maintained end to end across other call legs.

Configure the media mechanism through **SRTP Mode**. See [SRTP Mode
values](sip-trunk-settings-reference.html#inbound-sip-srtp-mode-values).

## SIP OPTIONS

DIDWW responds to SIP `OPTIONS` requests sent to the signaling addresses
used for inbound call delivery.

| Transport | Response port | Behavior |
| --- | --- | --- |
| UDP | `5060` | DIDWW responds to SIP `OPTIONS` over UDP. |
| TCP | `5060` | DIDWW responds to SIP `OPTIONS` over TCP. |
| TLS | `5061` | DIDWW responds to SIP `OPTIONS` over TLS. |

An `OPTIONS` response confirms SIP reachability. It does not indicate the
processing status of an inbound call.

## Firewall and SBC allowlist

| Traffic | Addresses or systems | Requirement |
| --- | --- | --- |
| Static Endpoint signaling | [Static Endpoint signaling addresses](#inbound-sip-static-signaling-endpoints) | Allow the signaling addresses for every DIDWW location that can deliver calls to the trunk. With **Preferred Server** set to **Auto**, allow all listed addresses. |
| Dynamic Registration signaling | [Dynamic Registration registrar addresses](#inbound-sip-connectivity-registrars) | Permit registration traffic to the selected registrar hostname and its resolved addresses, including the return signaling traffic. |
| RTP and RTCP | [RTP source subnets](#inbound-sip-connectivity-rtp) | Allow the listed media subnets and the `1024-65535` RTP port range. |
| DNS | Customer-configured DNS resolvers | Permit DNS resolution when a trunk uses a hostname, DNS SRV discovery, or `sip.didww.com`. |

The destination signaling port for a Static Endpoint must also be reachable
on the receiving SIP server. For the relationship between these flows, NAT,
and trunk settings, see [SIP connectivity](sip-connectivity.html).

## Machine-readable network data

A machine-readable version of the network data on this page is available as
JSON.

[voice.json](/voice.json)

Use the JSON data to configure and monitor firewall or SBC allowlists without
parsing this page.

## Related resources

- [SIP connectivity](sip-connectivity.html) - Understand how SIP signaling,
  media, routing, security, and monitoring work together.
- [SIP routing methods](sip-routing-methods.html) - Compare Static Endpoint
  and Dynamic Registration routing.
- [SIP trunk settings reference](sip-trunk-settings-reference.html) - Review
  the fields and values available on an inbound SIP trunk.
- [Configure Preferred Server routing](how-to-guides/configure-preferred-server-routing.html) - Control which DIDWW
  locations can deliver calls to a Static Endpoint trunk.

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