3CX Configuration for SIPcity

Add SIPcity as a SIP trunk in 3CX Phone System for inbound and outbound calling.

SIPcity supports two methods for connecting your 3CX Phone System to our SIP Trunking platform: SIP Registration (via username/password) and Static IP SIP Peering (no registration required). This guide covers both options, with a focus on Static IP SIP Peering for business-grade setups.

Prerequisites

  • 3CX v18 or later

  • A valid SIPcity trunk with either username/password credentials or a whitelisted IP for SIP Peering

  • Your outbound public IP must be known and stable (for IP-based peering)

Option 1: SIP Registration (Username and Password)

Use this method if SIPcity has issued credentials.

Trunk Setup

  1. Go to SIP Trunks > Add SIP Trunk

  2. Choose Generic SIP Trunk

  3. Set the following:

    • Registrar: sip.sipcity.com.au (or as provided)
    • Port: 5060 (UDP) or 5061 (TLS)
    • Authentication ID/Username: Your provided SIP user ID
    • Password: Your provided password

  4. Leave IP-based Authentication disabled

  5. Configure DID routing and codecs as needed

Option 2: Static IP SIP Peering (No Registration)

Recommended for customers with static IPs.

Enable Peering in SIPcity

  1. Log in to your SIPcity account

  2. Navigate to Switchboard

  3. Select your main peering phone number

  4. Go to Preferences

  5. Locate SIP Peering and enable it

  6. Enter your primary IP address (optionally add a failover IP address)

  7. Click Save

Create the SIP Trunk in 3CX

  1. Log in to the 3CX Management Console

  2. Go to SIP Trunks

  3. Select Add SIP Trunk

  4. Choose Generic SIP Trunk

General Tab

Setting

Value

Registrar/Server

103.55.116.65

Port

5060

Authentication

Leave blank

Username

Leave blank

Password

Leave blank

Options Tab

Setting

Value

Transport Protocol

UDP

SRTP

Disabled

Re-register Timeout

0

Public IP in SIP header

Leave blank

DID Numbers Tab

Add your SIPcity numbers exactly as issued. Example format: 6125638544

Route each DID to the appropriate extension, ring group, or IVR within 3CX.

Network Requirements

Setting

Value

SIP

UDP port 5060 to 103.55.116.65

RTP

UDP ports 9000–20,000

Outbound Rule Setup

Configure outbound rules to match numbers dialled by your users:

Setting

Value

Prefix

0, 00, 13, +

Strip Digits

No strip

Prepend

Leave blank

Outbound Caller ID

61756385444

Trunk

SIPcity (IP)

This rule allows local, mobile, international, and E.164 (+61) formatted numbers to route via SIPcity. Add a second rule for specific patterns (e.g. international 00 calls) if needed.

Troubleshooting

Symptom

Likely Cause

Fix

No outbound call

Number does not match an outbound rule

Add or correct dial prefixes

No SIP INVITE seen on SIPcity

3CX not matching a route

Create a fallback rule with X. prefix

“No user or outbound rule found” error

Dialled number doesn’t match rule

Review and test dial pattern

Outbound call fails with 403/404

Caller ID not valid

Set 61756385444 as outbound caller ID

Inbound calls working, outbound not

SIP trunk is inbound-only

Enable “Allow outbound calls” in trunk settings

Firewall and NAT

Ensure your outbound firewall rules allow:

  • UDP port 5060 from your PBX to 103.55.116.65
  • RTP media range: UDP ports 9000–10,999 (as per your 3CX RTP settings)
  • SIPcity must see your real public IP, not a translated one

Final Checklist

SIPcity has whitelisted your public IP

✓

3CX trunk set to “Do not require – IP based”

✓

Re-register timeout set to 0

✓

DID added in 3CX exactly as received

✓

Outbound rule matches all formats used by staff

✓

Summary

Although SIPcity is not a certified 3CX SIP trunking provider, many 3CX customers connect successfully via both registration and peering. We provide detailed connection guides, support for both methods, and have proven success with many 3CX customers across Australia and the US.