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:
Navigate to SIP Trunks in the left sidebar
Click Add SIP Trunk
Select Generic SIP Trunk from the provider list (or select IPComms if available in your 3CX version)
Enter a descriptive name like "IPComms SIP Trunk"
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
Registrar/Server/Gatewaysip.ipcomms.net
Outbound Proxysip.ipcomms.net
Number of SIM. CallsBased on your plan
Type of AuthenticationRegister/Account based
Authentication IDYour IPComms username
Authentication PasswordYour IPComms password
Building this? Your PBX will need a number
Find a phone number for your trunk
Local numbers $1.50 a month, toll-free $2.00, $1.00 one-time setup. Pick one here and it carries into signup.
Enter an area code, or wait a moment for numbers near you.
Outbound rules tell 3CX which calls to route through the IPComms trunk:
Go to Outbound Rules in the sidebar
Click Add to create a new rule
Name it "US/Canada Calls via IPComms"
Set the pattern to match the calls you want to route:
1NXXNXXXXXX - 11-digit US/Canada
NXXNXXXXXX - 10-digit US/Canada
011X. - International calls
Under Route, select your IPComms trunk
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:
Go to Inbound Rules in the sidebar
Click Add DID Rule
Enter the DID number from your IPComms account
Set the destination:
Extension - Route to a specific user
Ring Group - Ring multiple extensions
IVR - Route to auto-attendant
Queue - Route to call queue
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
Priority 1G.711 u-law (PCMU) - Best quality, 87 kbps
Priority 2G.711 a-law (PCMA) - Same quality, EU standard
Priority 3G.729 - Lower bandwidth, 32 kbps
OptionalOpus - HD voice, variable bitrate
Step 6: Testing Your Configuration
After saving your configuration, verify everything works:
Check trunk status: In the 3CX Dashboard, verify the IPComms trunk shows a green "Registered" status
Test outbound: Make a call to an external number and verify audio in both directions
Test inbound: Call your DID number from an external phone and verify it routes to the correct destination
Test caller ID: Verify your outbound caller ID displays correctly on the called party's phone
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.
