3CX SIP Trunk Configuration with IPComms

Prerequisites

Before you begin, make sure you have:

• A working 3CX Phone System installation (v18 or v20)
• An active IPComms SIP trunk account with credentials
• At least one DID (phone number) provisioned on your IPComms account
• Admin access to the 3CX Management Console
• Your 3CX server's public IP address (for IP authentication) or your SIP credentials (username/password)

Step 1: Add a New SIP Trunk

In the 3CX Management Console:

1. Navigate to SIP Trunks in the left sidebar
2. Click Add SIP Trunk
3. Select Generic SIP Trunk from the provider list (or select IPComms if available in your 3CX version)
4. Enter a descriptive name like "IPComms SIP Trunk"
5. Set the Main Trunk No. to your primary DID number from IPComms

Step 2: Configure Trunk Settings

On the trunk configuration page, enter these settings:

General Settings

Step 3: Create Outbound Rules

Outbound rules tell 3CX which calls to route through the IPComms trunk:

1. Go to Outbound Rules in the sidebar
2. Click Add to create a new rule
3. Name it "US/Canada Calls via IPComms"
4. Set the pattern to match the calls you want to route:
   • 1NXXNXXXXXX - 11-digit US/Canada
   • NXXNXXXXXX - 10-digit US/Canada
   • 011X. - International calls
5. Under Route, select your IPComms trunk
6. Set the Caller ID to use the trunk's default (your DID)

Step 4: Configure Inbound Rules

Inbound rules determine how incoming calls on your DIDs are handled:

1. Go to Inbound Rules in the sidebar
2. Click Add DID Rule
3. Enter the DID number from your IPComms account
4. Set the destination:
   • Extension - Route to a specific user
   • Ring Group - Ring multiple extensions
   • IVR - Route to auto-attendant
   • Queue - Route to call queue
5. Optionally configure Office Hours routing for after-hours handling

Step 5: Codec Configuration

Proper codec selection ensures call quality and efficient bandwidth usage. Configure these in your trunk settings:

Recommended Codec Priority

Step 6: Testing Your Configuration

After saving your configuration, verify everything works:

1. Check trunk status: In the 3CX Dashboard, verify the IPComms trunk shows a green "Registered" status
2. Test outbound: Make a call to an external number and verify audio in both directions
3. Test inbound: Call your DID number from an external phone and verify it routes to the correct destination
4. Test caller ID: Verify your outbound caller ID displays correctly on the called party's phone
5. Test failover: If you have a backup trunk, verify calls route to it when the primary is unavailable

Troubleshooting

Trunk shows "Failed" or "Timeout"

Verify your firewall allows outbound UDP/5060 and TCP/5061 to sip.ipcomms.net. Also check that your credentials are correct and your account is active.

One-way audio

Usually a NAT issue. Ensure your 3CX STUN server is configured and that RTP ports (9000-10999 by default) are forwarded to your 3CX server.

Inbound calls not arriving

Check that your firewall allows inbound SIP from IPComms (34.23.59.14) and that your inbound DID rule matches the number format IPComms sends.

Outbound calls fail with 403

A 403 Forbidden usually means authentication failed or the calling number is not authorized. Verify your credentials and ensure the caller ID is set to a DID on your account.

Get SIP Trunks for Your 3CX System

IPComms provides reliable, high-quality SIP trunking with full 3CX compatibility. Competitive per-minute rates with no contracts or channel commitments.