diff --git a/fern/advanced/sip/troubleshoot-sip-trunk-credential-errors.mdx b/fern/advanced/sip/troubleshoot-sip-trunk-credential-errors.mdx
index fa43fe560..0fbc96965 100644
--- a/fern/advanced/sip/troubleshoot-sip-trunk-credential-errors.mdx
+++ b/fern/advanced/sip/troubleshoot-sip-trunk-credential-errors.mdx
@@ -36,15 +36,18 @@ This is the most common cause of this error.
### What happens
-Vapi's API accepts both hostnames (for example, `sip.example.com`) and IPv4 addresses (for example, `203.0.113.10`) in the `gateways[].ip` field. However, the underlying SBC only accepts IPv4 addresses. When you provide a hostname, the SBC rejects the gateway configuration.
+Vapi's API accepts both hostnames (for example, `sip.example.com`) and IPv4 addresses (for example, `203.0.113.10`) in the `gateways[].ip` field. However, **hostnames only work for outbound-only gateways**. For inbound-enabled gateways, the SBC requires a numeric IPv4 address to match the origin of incoming SIP requests. When you provide a hostname for an inbound-enabled gateway, the SBC rejects the gateway configuration.
### How to check
-Look at the value you passed in `gateways[].ip`. If it contains letters (for example, `sip.example.com`), it is a hostname. The SBC needs a numeric IPv4 address instead.
+Look at the value you passed in `gateways[].ip` and the `inboundEnabled` setting:
+
+- If `inboundEnabled` is `true` (the default) and `gateways[].ip` contains a hostname (for example, `sip.example.com`), this is the problem. Inbound gateways require a numeric IPv4 address.
+- If `inboundEnabled` is `false` (outbound-only), hostnames are accepted and this is not the cause of your error.
### How to fix
-Resolve the hostname to its IPv4 address, then use that IP directly.
+If your gateway has inbound enabled, resolve the hostname to its IPv4 address, then use that IP directly.
@@ -76,7 +79,7 @@ Replace the hostname with the numeric IPv4 address in your gateway configuration
"ip": "203.0.113.10",
"port": 5060,
"outboundEnabled": true,
- "inboundEnabled": false
+ "inboundEnabled": true
}
]
}
@@ -86,8 +89,9 @@ Replace the hostname with the numeric IPv4 address in your gateway configuration
- Always use the IPv4 address, not the hostname. If your provider's IP changes,
- you need to update the gateway configuration.
+ Hostnames are supported for outbound-only gateways (`inboundEnabled: false`).
+ For inbound-enabled gateways, always use a numeric IPv4 address. If your
+ provider's IP changes, you need to update the gateway configuration.
## Inbound enabled on an outbound-only trunk
@@ -157,7 +161,7 @@ The table below lists all available options for each entry in the `gateways` arr
| Option | Type | Default | Description |
| -------------------- | ------- | --------- | ------------------------------------------------------------------------------ |
-| `ip` | string | (required)| IPv4 address of your SIP gateway. Must be a numeric IP address, not a hostname.|
+| `ip` | string | (required)| Server address of your SIP gateway. Use a numeric IPv4 address for inbound-enabled gateways. Hostnames are accepted for outbound-only gateways (`inboundEnabled: false`).|
| `port` | number | `5060` | SIP signaling port. |
| `netmask` | number | `32` | Subnet mask for inbound IP matching. Valid range: 24 to 32. |
| `inboundEnabled` | boolean | `true` | Whether this gateway accepts inbound calls. Set to `false` for outbound-only trunks. |