Viking Advanced Two Door Entry Phone Controller with Call Forwarding and Door Strike Control - C-500

Viking Electronics C-500 Two Door Entry Phone Controller

Overview

The Viking Electronics C-500 is a telephone-line-powered, two-door entry phone controller built for commercial lobby, multi-tenant, and light industrial access control applications where you need call forwarding to an internal extension or off-site number — without running dedicated access control infrastructure. The C-500 handles up to two independent entry points, provides two dedicated door strike relay outputs, and supports call forwarding so personnel can answer and release a door strike from virtually any phone on the system. If you've been trying to solve after-hours remote entry without installing a full access control panel, this controller is the targeted solution.

The unit measures 5.25" x 4.1" x 1.75" and ships with a UL listed power adapter. Operating range is 32°F to 90°F at 5–95% non-condensing humidity — appropriate for conditioned entry vestibules and climate-controlled utility closets, but not unheated exterior enclosures without supplemental thermal management.

Key Features

• Two Independent SPDT Door Strike Relays: Each relay is rated 5A at 30VDC or 250VAC and provides both normally-open and normally-closed contacts. That SPDT configuration means you can wire fail-secure or fail-safe strikes on the same controller without external relay modules — a practical time-saver on two-door vestibule installs.
• Call Forwarding with Remote Door Release: The C-500 routes entry phone calls through the telephone system to any designated extension or off-site number, letting staff answer and release the door strike from wherever they happen to be. This is the defining feature for unmanned lobbies or after-hours access scenarios where a dedicated guard station isn't feasible.
• Distinctive Ring Detection: Optional entry phone distinctive ring support lets the system differentiate a door station call from a standard voice call on the same line — so the receptionist or answering party knows immediately it's a door event, not a routine inbound call.
• Nine Keyless Entry Codes: The controller supports six permanent codes, two one-time-use codes, and one toggle code. The two single-use codes are useful for contractor or temporary visitor access — they expire after first use without requiring you to reprogram the entire code set. The toggle code is well-suited for controlled propped-door scenarios during loading operations.
• Two Trigger Inputs for Request-to-Exit: Both trigger inputs are field-programmable, making it straightforward to wire REX (Request to Exit) motion sensors or push-button exits at each door — a baseline code compliance requirement for many egress paths in commercial settings.
• 1000 ft Maximum Wire Run on CAT5E: At up to 1000 feet on CAT5E, the C-500 can reach entry stations at the perimeter of mid-size commercial buildings without signal degradation. If your nearest entry point is across a parking structure or at a loading dock 600 feet from the head-end, this spec matters — many competitive units max out at 500–600 ft.
• 5 REN Ring Output: A 5 REN ring output means the controller can drive multiple ringers or phone sets on the same line without overloading the ring generator — relevant when you're distributing ring signals to more than one desk phone in an open-plan office.
• 44V DC Talk Battery: The 44V DC talk battery ensures reliable audio levels over the full 1000 ft wire run, avoiding the faded or choppy audio that lower-voltage talk batteries produce at distance.
• Caller ID Support: Field-programmable Caller ID display or beep tones when the entry call is answered gives the receiving party immediate context about which door is calling — useful in a two-door install where the response action may differ by entry point.
• 120VAC Power with UL Listed Adapter: Standard 120VAC input via included UL listed adapter simplifies installation and satisfies most AHJ requirements without sourcing a separate listed power supply.

Integration and Compatibility

The C-500 integrates into any standard telephone system — analog POTS lines, PBX analog extensions, or VoIP ATAs that present a standard analog interface. It is not a SIP endpoint; it requires an analog telephone interface at the installation point. The dual SPDT relay outputs are compatible with the vast majority of commercial electric door strikes, magnetic locks (with appropriate power supply), and electronic latch releases. For access control software integration, the trigger inputs provide a clean contact closure path for REX devices, and the relay outputs can be monitored by external control systems via the N.C. contact. Wire the controller using access control wiring best practices — CAT5E is confirmed to 1000 ft, but avoid running door station lines parallel to high-voltage conductors to prevent induced noise on the talk path.

The C-500 is a product from the Viking Electronics entry phone and intercom line — a catalog that covers everything from single-door analog units to more complex multi-door controllers. If you're evaluating the C-500 alongside other door entry controllers, the key differentiators here are the call forwarding capability and the 1000 ft CAT5E reach. For installations requiring IP-based management, app-based mobile unlock, or video at the door station, the C-500 is not the right platform — those requirements call for a networked video intercom or IP access control system. Pair the C-500 with a compatible electric door strike or magnetic lock appropriate for your door type and fail-state requirement.

Frequently Asked Questions

Q: Can the C-500 control two separate doors simultaneously, or only one at a time?

A: The C-500 provides two independent SPDT door strike relay outputs, each rated 5A at 30VDC or 250VAC, so it can control two separate doors. Each relay operates independently and can be wired for fail-secure or fail-safe configurations.

Q: Does the C-500 require a dedicated phone line, or can it share an existing line?

A: The C-500 is telephone-line powered and integrates with standard analog telephone systems, including PBX analog extensions. It does not require a dedicated line, though sharing behavior depends on your telephone system's configuration and distinctive ring support.

Q: What is the maximum wire distance between the C-500 and an entry phone station?

A: The C-500 supports a maximum wire run of 1000 feet using CAT5E cable, making it suitable for larger commercial installations where the entry station is at a significant distance from the controller.

Q: How many entry codes does the C-500 support, and can codes be limited to single use?

A: The C-500 supports nine keyless entry codes: six permanent codes, two one-time-use codes that expire after first entry, and one toggle code. The one-time-use codes are useful for temporary contractor or visitor access without requiring a full code reprogramming.

Q: What are the operating environment requirements for the C-500?

A: The C-500 is rated for 32°F to 90°F operating temperature and 5–95% non-condensing relative humidity. It is designed for conditioned indoor environments such as entry vestibules or utility closets, not unheated exterior enclosures.

Q: Does the C-500 support Request-to-Exit (REX) devices?

A: Yes. The C-500 includes two field-programmable trigger inputs specifically designed to support Request-to-Exit motion sensors or push-button exit devices, one per door, which is a standard code compliance requirement on many commercial egress paths.

James Everett

The C-500 (also searched as C 500) comes up regularly in light commercial projects where the customer needs two-door access with remote answer-and-release and the budget or infrastructure doesn't support a full IP access control deployment. The 1000 ft CAT5E reach is the spec I'd highlight first — most sites I see have entry stations that are 300–700 ft from the IDF or head-end closet, and hitting that distance reliably on standard structured cabling without a repeater is where the C-500 earns its place.

Technical Highlights:

• Dual SPDT Relay Outputs (5A @ 30VDC/250VAC): The normally-open and normally-closed contacts on each relay give you full wiring flexibility — fail-secure strikes and mag locks on the same controller, no external relay board required.
• Nine Keyless Codes Including Two One-Time-Use: The two single-use codes are genuinely useful for contractor access. They expire on first use, which eliminates the common oversight of forgetting to revoke a temporary code after the work is done.
• 44V DC Talk Battery at 1000 ft: Talk battery at that voltage sustains audio quality across the full wire run. At 500+ feet on lower-voltage controllers you often hear degraded audio; the C-500's 44V spec prevents that on long runs.

Deployment Considerations:

• The C-500 requires an analog telephone interface — if your facility has migrated entirely to SIP endpoints with no ATA, plan for an ATA at the installation point before the controller will function correctly.
• Operating temperature tops out at 90°F — in a mechanical room or utility space that runs hot in summer, verify ambient temperature before mounting. An unventilated IDF closet in a sunbelt facility can easily exceed that ceiling in July.

The C-500 is the right call for a two-door commercial lobby or multi-tenant building entry where analog telephone infrastructure is already in place and the integrator needs call forwarding, REX inputs, and flexible door strike wiring without the cost or complexity of an IP access control panel.