Phone systems (PBX)
Your office keeps its phone system, its lines and its numbers. Voice Logica connects to the phone system, and from then on the PBX decides which calls the AI agent answers, and the agent can hand callers back to your extensions.
This section explains how Voice Logica connects to your phone system, then gives the exact steps for each make.
The four ways Voice Logica connects
Section titled “The four ways Voice Logica connects”| How the connection is made | Use it when | |
|---|---|---|
| 1. Your PBX registers a SIP trunk to Voice Logica (recommended) | Voice Logica creates a trunk with its own server, username and password. You enter them on the PBX as if Voice Logica were a phone provider. The PBX connects out to us. | The PBX can add a SIP trunk / SIP provider / ITSP. Almost every IP PBX can, sometimes with a licence or a VoIP card. |
| 2. Voice Logica registers as an extension on your PBX | The PBX creates one SIP extension for Voice Logica. An edge device inside the office registers to the PBX as that extension and carries the calls to us over an encrypted tunnel. | The PBX has no SIP trunk licence, but can take SIP extensions. |
| 3. A SIP gateway in front of an analog or ISDN system | A small gateway connects to the PBX’s analog or ISDN ports on one side and registers to Voice Logica (way 1) on the other. | The PBX has no SIP at all: older analog or ISDN systems. See Analog and ISDN systems. |
| 4. Forward the number, leave the PBX as it is | Your carrier forwards the number (or only unanswered or busy calls) to a Voice Logica number. The agent transfers to direct numbers or mobiles. | You do not want to touch the PBX, or need to go live today. See Forward your number. |
In ways 1 to 3 nothing is opened on your firewall: the PBX, the gateway or the edge device always connects outwards, so the PBX needs no public IP and no port forwarding.
What happens on a call
Section titled “What happens on a call”Calls to the agent. On the PBX you choose which calls go to the trunk (or to the Voice Logica extension): a number (DDI/MSN), an IVR option, a queue overflow, after-hours calls, or a short code your staff dial. Voice Logica answers every call on that trunk with the agent you picked.
Transfers back to your people. The agent sends the caller back to the PBX on the same connection, and the PBX rings the extension with its own dialplan:
- add the extension number (for example
201) as an External destination on the agent, or - add the person as a User with their extension number. If they are signed in to a Voice Logica app, the app rings; otherwise the call goes back to the PBX extension.
With Warm transfer the caller hears hold music and is connected only when the person answers. If nobody answers in time, the agent comes back to the caller and takes a message. Out of hours the agent does not try a transfer at all. See Transfer.
Channels. Each call with the agent uses one channel on the trunk. During a Warm transfer the call uses two (the caller and the extension) until it is connected. Size the PBX’s SIP channels or licences for that.
What Voice Logica gives you
Section titled “What Voice Logica gives you”When you click Telephony - Trunks - Connect your PBX (or ask Claude or ChatGPT to “connect my PBX”), Voice Logica creates the connection and shows:
| On the PBX | Value |
|---|---|
| Server, registrar, proxy, domain | <your-company>.sip.voicelogica.ai |
| Port | 5060 UDP (5061 TLS) |
| Username and authentication ID | generated, for example pbx123456 |
| Password | generated, shown once |
| Registration | on |
| Codecs | G.711 A-law first, then G.711 u-law |
| DTMF | RFC 2833 / RFC 4733 |
The dialog changes to Connected as soon as the PBX registers. Full walkthrough: Connect your PBX.
Pick your phone system
Section titled “Pick your phone system”Before you start
Section titled “Before you start”- Who changes the PBX. Usually your PBX maintainer or installer. Send them the page for your make and the values from the dialog.
- Licences and cards. Many PBXs need a SIP trunk licence, a VoIP/DSP card or both. Each make’s page lists them under Before you start.
- Internet access for the PBX. Outbound UDP 5060 to Voice Logica and outbound RTP audio. Nothing inbound.
- SIP ALG off on the office router or firewall. It rewrites SIP and is the most common reason a trunk does not register or has no audio.
Ask for help
Section titled “Ask for help”- In the app, the Ask AI button in the Connect your PBX dialog opens Claude or ChatGPT with your make already in the question, answered from these pages.
- With the Voice Logica connector, Claude or ChatGPT creates the connection, walks your maintainer through the PBX menus one step at a time and checks the registration.
- Our team can talk to your PBX maintainer directly: open a support ticket.
Questions
Section titled “Questions”Do my numbers or lines change?
No. In ways 1 to 3 the lines and numbers stay on the PBX, and the trunk only carries the calls the PBX sends to the agent and the transfers back. In way 4 the numbers stay with your carrier and are forwarded.
My PBX is not listed.
If it can add a SIP trunk that registers to a provider, use the values above: see Other makes. If it has no SIP, see Analog and ISDN systems.
Trunk or extension: which is better?
A trunk (way 1). Voice Logica can take several calls at once on it and transfer back to any extension. As an extension (way 2) the PBX treats Voice Logica as one phone, so how many calls reach it at once and how transfers work follow that extension’s settings, and it needs an edge device on site.