Connect 3CX to 2talk SIP Trunking

Connect 3CX to 2talk SIP Trunking with SIP registration or static IP peering for inbound and outbound calls.

2talk supports two methods for connecting your 3CX Phone System to our SIP Trunking platform:

  • SIP Registration (using a username and password)
  • Static IP SIP Peering (no registration required)

This guide walks through both options. Static IP SIP Peering is recommended for business-grade setups with a stable public IP address.

Prerequisites

  • 3CX v18 or later.
  • An active 2talk trunk with either SIP credentials or a whitelisted IP for peering.
  • A known, stable outbound public IP address (required for IP-based peering).

Option 1: SIP Registration (Username and Password)

Use this method if 2talk has issued you SIP credentials.

Trunk setup

  1. In 3CX, go to SIP Trunks > Add SIP Trunk.
  2. Choose Generic SIP Trunk.

  3. Enter the following values:

    • Registrar: plus.2talk.com
    • Port: 5060 (UDP) or 5061 (TLS)
    • Authentication ID / Username: the SIP user ID provided by 2talk
    • Password: the password provided by 2talk
  4. Leave IP-based Authentication disabled.
  5. Configure DID routing and codecs (we recommend PCMU first, then PCMA, for US customers).

Option 2: Static IP SIP Peering (No Registration)

Recommended for customers with a static public IP address.

2talk provisioning

Provide your 3CX server’s public IP to 2talk so we can add it as a SIP Peering endpoint. For example:

  • Primary Peer IP: your 3CX public IP (for example, 203.0.113.10)
  • Destination Proxy: 27.111.12.66:5060

3CX configuration

General tab

  • Registrar/Server: 27.111.12.66
  • Port: 5060
  • Authentication: select Do not require – IP based. Leave the username and password fields blank.

Options tab

  • Transport Protocol: UDP
  • SRTP: Disabled
  • Re-register Timeout: 0 (this prevents 3CX from sending REGISTER packets, which is correct for IP peering)
  • Public IP in SIP Header: leave blank unless required

DID Numbers tab

  • Add your 2talk number(s) exactly as 2talk delivers them (for example, 13106341786).
  • Route each DID to the correct extension or ring group.

Outbound rule setup

To match the numbers your users dial, configure an outbound rule on the 2talk trunk. The example below covers local US, toll-free, international, and E.164-formatted numbers.

Setting Value
Prefix 1, +, 011, 800
Strip Digits No strip
Prepend Leave blank
Outbound Caller ID Your 2talk DID (for example, 13106341786)
Trunk 2talk SIP

Tip: add a second rule with the X. pattern as a fallback to catch any unmatched dial strings.

Troubleshooting

Symptom Likely cause Fix
No outbound call Number doesn’t match an outbound rule Add or correct dial prefixes
No SIP INVITE seen on 2talk 3CX isn’t matching a route Create a fallback rule with the X. prefix
“No user or outbound rule found” error Dialed number doesn’t match a rule Review and test the dial pattern
Outbound call fails with 403/404 Caller ID isn’t valid Set a valid 2talk DID as the Outbound Caller ID
Inbound calls work but outbound doesn’t SIP trunk is inbound-only Enable Allow outbound calls in the trunk

Firewall and NAT

Make sure your outbound firewall rules allow:

  • UDP 5060 from your PBX to 27.111.12.66 (or the 27.111.12.0/24 range).
  • RTP media range: UDP 9000–10999 (or whatever your 3CX RTP settings specify).
  • 2talk should see your real public IP, not a translated one. Confirm that NAT and SIP ALG are not rewriting your SIP headers.

Final checklist

  • 2talk 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 every number format your team dials.

Summary

2talk isn’t listed as a certified 3CX SIP trunking provider, but many 3CX customers connect successfully using either Registration or IP Peering. We provide detailed connection guides, support both authentication methods, and have a track record of successful 3CX deployments across the United States.

If you run into trouble, contact 2talk Support with your trunk ID, public IP, and a sample SIP capture so we can help quickly.

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