Skip to main content

How to Connect a SIP Trunk

A SIP trunk connects 4phone to your telecom carrier. The platform uses it to receive and place calls.

What to Prepare in Advance​

Before creating a trunk, request the following details from your provider:

  1. SIP server address;
  2. port;
  3. transport protocol: UDP, TCP, or TLS;
  4. username and password, if the provider uses registration;
  5. Caller ID name and number, if the provider requires specific values;
  6. authentication method: by username and password, or by IP address.

How to Fill Out the Form​

Click Add Trunk and fill in the fields:

  1. Name. Any descriptive name, for example Primary Provider.
  2. Host. The provider's server address, for example sip.provider.com.
  3. Port. Usually 5060, though it may vary.
  4. Username and Password. Required if the provider uses registration.
  5. Transport. Select the protocol required by your provider: UDP, TCP, or TLS.
  6. Caller ID Name and Caller ID Number. Fill these in if your provider expects specific identification values.
  7. Channels. The maximum number of concurrent calls allowed through this trunk.
  8. Register on provider server. Enable this if the provider gave you a username and password specifically for SIP registration.
Tip

If your provider uses IP authentication, disable registration. The trunk will operate with the status Active (IP Auth).

What Happens After Saving​

After you save, 4phone automatically applies the settings and checks the connection to your provider. Click the Diagnostics button (the flask icon next to the trunk in the list) to view the current status.

How to Read Diagnostics​

Diagnostics shows the current state of the trunk, a helpful hint, and call statistics. If something is not working, the hint panel explains the likely cause.

Status in UIMeaning
RegisteredRegistration with the provider succeeded; the trunk is working
Active (IP Auth)The trunk operates without registration; the provider authenticates by IP
Connecting...Attempting to connect to the provider
DisconnectedThe trunk is not in an operational state
Registration FailedThe provider rejected the registration
Server UnreachableUnable to communicate with platform servers to check status
ConfiguringSettings are being applied; wait a moment and run diagnostics again
ErrorGeneral error; see the diagnostics hint for details
Check

The Registration Failed status does not always mean an incorrect password. An wrong host, mismatched transport protocol, or enabling registration on an IP-authenticated trunk can produce a similar result. Check the hint in the diagnostics panel for the specific reason.

In addition to status, diagnostics displays:

  • Uptime -- how long the trunk has been active.
  • Inbound / Outbound -- call counters through this trunk.
  • Inbound Errors / Outbound Errors -- counters for failed attempts.

If anything is unclear, click Check Again to re-run diagnostics.

Common Issues​

Trunk shows "Connecting..." and never becomes active​

The platform is trying to connect to the provider but is not receiving a response.

What to check:

  1. accuracy of the host and port;
  2. whether the transport protocol (UDP/TCP/TLS) matches the provider's requirements;
  3. reachability of the provider's server.

Trunk shows "Registration Failed"​

What to check:

  1. username and password;
  2. whether registration mode is actually needed -- the provider might use IP authentication instead;
  3. whether your server's IP address is allowlisted on the provider's side.

Trunk is active, but outbound calls fail​

If the trunk shows an operational status but outbound calls do not go through, check:

  1. whether you have at least one active outbound trunk;
  2. whether the channel limit has been exceeded;
  3. whether the dialed number format matches your provider's requirements.

If the issue is number formatting -- for example, calls without +998 go through while calls with +998 fail -- configure a rule in Outbound Routes and Number Formatting.

Best Practices​

After configuring a trunk
  1. Open diagnostics and confirm the status is operational.
  2. Place one test outbound call.
  3. If you have a DID number, test an inbound call as well.
  4. Only then proceed to configuring routes and automation.

Next, users typically open Outbound Routes and Number Formatting, How to Configure a DID Number and Route, or What SIP Trunk Statuses Mean.