Quick Answer: SIP door entry and access control integration is the process of registering a door intercom as a SIP endpoint on a VoIP phone system, so a visitor button press rings an extension or ring group, and an answering user releases the door with a DTMF code that triggers the intercom's onboard relay. It turns a door station into another managed extension on the same platform.
TL;DR
- A SIP door station registers to your PBX as a standard extension, so no special gateway is required for audio door entry.
- A visitor button press sends a SIP INVITE to an extension, ring group, or hunt group, and the device auto-answers for two-way audio.
- Door release is handled by a DTMF code entered during the call, which fires a dry-contact relay on the intercom or its controller.
- Power the device with PoE, and budget IEEE 802.3at if the door strike draws power from the unit.
- Two-piece controller-plus-station designs keep the relay and network connection inside the secure perimeter to resist tampering.
- Video door stations add ONVIF so the camera feed lands in the same VMS as the rest of the building.
- For resellers, door entry is a high-margin attach to every voice deal and rarely competes with the core phone sale.
What SIP Door Entry and Access Control Integration Is
SIP door entry and access control integration is the practice of treating a door intercom as a Session Initiation Protocol endpoint on the same VoIP platform that runs the desk phones. The door station registers with a username, password, and SIP server address exactly like a handset, which means it can call extensions, sit in ring groups, and be reached by any device on the platform. Session Initiation Protocol is the IETF signaling standard defined in RFC 3261 that sets up and tears down voice sessions, and a compliant door station speaks it natively.
The access control half of the job is the relay. Most IP door stations include a dry-contact relay, on the unit or on a separate controller, that connects to an electric strike, magnetic lock, or gate operator. The relay is what physically releases the door, and on a SIP device it is triggered by a touch-tone code sent during the call.
Why MSPs Are Being Asked for This in 2026
Door entry sits at the intersection of two budgets that are both growing: voice and physical security. As of Q3 2026, more of that spend is landing on IP-based, network-attached devices that an MSP can install and manage rather than a separate alarm contractor.
For a reseller already delivering a hosted VoIP platform, the door station is an attach sale that uses skills the team already has. There is no new dial tone to provision and no second vendor relationship. The intercom is one more endpoint on a system the MSP already owns.
The commercial case is straightforward once you account for install time. A voice technician already on site for a phone deployment can typically add a door station in an afternoon, since the network drop, PoE budget, and VLAN work overlap with what they are already doing for the desk phones. Compare that to bringing in a separate alarm or security integrator, who has to quote, schedule, and bill the job independently, and the door station attach starts to look like one of the cleanest incremental revenue lines an MSP can add without hiring a new specialty.
How a SIP Door Station Actually Works on a VoIP System
A SIP door station follows the same call flow as any other extension, with two differences: the trigger is a physical button, and the call can release a door.
What happens when a visitor presses the button? The door station sends a SIP INVITE to a preconfigured destination. That destination can be a single extension, a ring group of several phones, or an auto attendant. The receiving phone rings, the user answers, and two-way audio is established so the user can speak with the visitor. Many deployments also allow the reverse: an internal user can dial the door station extension directly, and the unit auto-answers for a two-way call.
How does the door actually unlock? During the live call, the answering user presses a configured code on the phone keypad, for example a single digit or a string of up to four digits, and that DTMF tone tells the intercom to close its relay for a set number of seconds. Those touch-tone digits travel as named telephone-events under RFC 4733, the modern standard that replaced RFC 2833. The relay duration, the unlock code, and the called extension are all set in the door station's web interface.
Entity definitions. A SIP door station is a network intercom that registers to a VoIP PBX as a SIP endpoint and converts a button press into an outbound call. A dry-contact relay is an electrically isolated switch, typically rated around 30V at 1A on devices like the Algo 8028, that opens or closes a circuit to a door strike or maglock. A ring group is a PBX construct that rings multiple phones at once so a visitor reaches whoever is available.
Step-by-Step: Integrating a SIP Door Station
- Create an extension for the door. On the PBX, build a dedicated extension or SIP user for the door station with its own credentials. Treat it like a phone, not a special device.
- Register the door station. In the unit's web GUI, enter the register name, SIP user, password, and SIP server. When it shows registered, it is reachable on the platform.
- Set the call destination. Configure the button to call a single extension during the day and a ring group or after-hours destination outside business hours. Time-based routing on the PBX keeps the front door reaching a real person.
- Configure the unlock code and relay. In the door station, set the DTMF open code and the relay activation time, a few seconds is typical. Confirm whether the strike is powered by the unit or by a separate supply, because that drives your PoE class.
- Wire the relay to the strike or maglock. Connect the relay to the door hardware as normally open or normally closed depending on whether the door should be fail-secure or fail-safe. Follow the strike manufacturer's wiring and local fire code.
- Add fallback routing. Route unanswered door calls to a mobile app, softphone, or voicemail so a missed front-desk call does not strand a visitor.
- Test the full path. Press the button, answer on each target device, enter the code, and confirm the door releases for the configured time. Test during and outside business hours.
Door Entry Hardware MSPs See Most
The SIP door station market is broad, and most leading vendors build third-party SIP compliance so the device works with most hosted and premise PBXs. The hardware an MSP encounters most often includes Algo, the 2N line, CyberData, Fanvil, including its i60 video door phone, Grandstream's GDS and GSC families, Akuvox, and DNAKE. Ubiquiti UniFi Access and Hikvision also appear, though some of those lean on their own ecosystems rather than open SIP registration.
| Capability | What to Look For | Why It Matters for MSPs |
|---|---|---|
| SIP compliance | Third-party SIP endpoint, not a closed ecosystem | Registers to your PBX as a standard extension with no gateway |
| Relay location | Two-piece controller plus station | Keeps the relay and network drop inside the secure perimeter |
| Power | PoE, IEEE 802.3af or 802.3at if powering the strike | One cable for power and data, no separate transformer run |
| Audio | Wideband HD voice | Intelligible speech at a noisy entrance |
| Video | ONVIF support | Camera feed lands in the same VMS as the building's other cameras |
| Security | SIP over TLS and SRTP | Encrypts signaling and media on the door extension |
For buyers still choosing endpoints, our guide to the best VoIP phones to resell covers door and access devices alongside desk phones, and the paging adapter wiring guide covers the closely related overhead paging build.
Security and Network Design
A door station is a publicly accessible device wired to a lock, so design matters. Three rules cover most deployments.
Keep the relay inside the perimeter. On two-piece systems, the controller that holds the relay and the network connection lives inside the building. If someone rips the outdoor station off the wall, they reach a button, not the lock circuit or the LAN.
Put the door station on the voice VLAN and encrypt it. The door extension belongs on the same segmented voice VLAN as the phones, with SIP over TLS and SRTP enabled where the device and platform support it. Clean network policy at the edge is the same discipline that keeps the rest of the deployment healthy, which is why our Ubiquiti QoS guide and FortiGate VoIP configuration guide apply here too.
Power the device for its real load. A bare audio intercom runs on IEEE 802.3af. If the unit also powers the strike, you likely need IEEE 802.3at, or PoE+, which delivers up to 30W at the source. Confirm the strike's voltage and current draw before you size the switch port.
Troubleshooting Matrix
| Symptom | Likely Cause | First Check |
|---|---|---|
| Door station will not register | Wrong SIP credentials or blocked signaling | Verify SIP user, password, server, and that SIP ALG is off on the firewall |
| Button press does not ring anyone | Call destination not set or ring group empty | Confirm the button maps to a valid extension or ring group |
| Call connects but door will not open | Wrong DTMF code or DTMF mode mismatch | Match the open code and set RFC 4733 telephone-event mode on both ends |
| One-way or no audio | NAT or SIP ALG rewriting media | Disable SIP ALG and confirm the door station is on the voice VLAN |
| Device reboots or strike fails under load | Insufficient PoE class | Move to an 802.3at port or add a dedicated strike power supply |
| Door unlocks too briefly | Relay timer too short | Raise relay activation seconds in the device GUI |
Where Viirtue Fits
Viirtue's hosted PBX registers third-party SIP door stations as standard extensions, so an MSP can add door entry to an existing customer without a separate access control platform or a gateway box. That is the practical advantage over two common alternatives. SIP-only or trunk-only providers give you dial tone but no integrated PBX features like ring groups, time-based routing, and a managed extension for the door. Closed consumer ecosystems lock the intercom to their own app and cloud, which strands the MSP outside the management path.
Because Viirtue runs on a carrier-grade voice network with the quoting, billing, and telecom tax handled inside ViiBE, a reseller can package the door station, the desk phones, and the seats as one branded, billed line of business. Door entry also pairs naturally with after-hours handling: calls that go unanswered at the front desk can route to a mobile app, a softphone, or an automated greeting so a visitor is never met with silence.
That single-platform billing matters more than it sounds. A door station that lives on a separate access control vendor's invoice is a line item the partner has to track, reconcile, and support outside their core voice contract. When the door extension bills through the same platform as the rest of the seats, it is one invoice, one support queue, and one renewal conversation instead of three.
A SIP door station is just another registered extension, which is what makes the integration simple. The unlock is a DTMF code that fires a dry-contact relay, so get the code and relay timer right before you wire the strike. Size PoE for the real load, 802.3af for audio only and 802.3at when the unit powers the strike, and use a two-piece design so the relay and LAN stay inside the perimeter. For MSPs, that combination makes door entry a low-friction, high-margin attach to every voice deal.
SIP Door Entry and Access Control Integration: The Bottom Line
Integrating a SIP door entry and access control system is mostly extension provisioning plus one relay decision. Register the door as a SIP endpoint, route the button to the right people, set the DTMF unlock code, and power the device for its real load. For MSPs, it is one of the easiest ways to grow revenue on accounts you already manage.
If you want to scope a door entry attach for a customer, start with a quick network check using Viirtue's VoIP readiness test, or talk to us about Viirtue's white label partner program.
FAQ: SIP Door Entry and Access Control Integration
What is a SIP door station?
A SIP door station is a network intercom that registers to a VoIP PBX as a SIP endpoint. A visitor button press places a call to an extension or ring group, and the device can release a connected door via a DTMF code during the call.
How does a VoIP door entry system unlock the door?
The answering user enters a preconfigured DTMF code on the phone keypad during the call. That tone tells the intercom to close its onboard relay for a set number of seconds, which releases the electric strike or magnetic lock.
Do I need a special gateway to integrate a door intercom?
No. A 3rd-party SIP-compliant door station registers directly to the PBX like a handset. A gateway or ATA is only needed for legacy analog intercoms that are not SIP capable.
Can a door station ring more than one phone?
Yes. Point the button at a ring group or hunt group so multiple phones ring at once, and add time-based routing so after-hours calls reach a mobile app or softphone.
What PoE standard does a door station need?
Audio-only intercoms typically run on IEEE 802.3af. If the unit also powers the door strike, plan for IEEE 802.3at (PoE+), which supplies up to 30W at the source.
Can I add video to a SIP door entry system?
Yes. Video door stations that support ONVIF can stream into the same video management system as the building’s other cameras, so the entrance feed is not siloed.
Is a VoIP door entry system secure?
It can be. Use a two-piece design that keeps the relay inside the perimeter, place the door extension on a segmented voice VLAN, and enable SIP over TLS and SRTP where supported.
