Poly API-28 3.5mm Electronic Hook Switch for iPhone and CS500 Series

Poly API-28 3.5mm Electronic Hook Switch for iPhone and CS500 Series

The Poly API-28 is a 3.5 mm electronic hook switch cable designed to connect a compatible Poly CS500 or CS500 XD wireless headset system to selected Apple iPhones. It routes call audio through the wireless headset system and allows supported incoming calls to be answered from the headset’s call-control button. This is a legacy accessory intended for older iPhones equipped with a built-in 3.5 mm headset socket.

Use a CS500 Headset with a Compatible iPhone

The API-28 connects the 3.5 mm headset socket on a supported iPhone to the base of a compatible CS500 wireless headset system. This allows the mobile phone’s call audio to be handled through the wireless headset rather than through the phone itself.

Remote Mobile Call Answering

When the API-28 is correctly connected and the headset base is configured, an incoming mobile call can be answered using the call-control button on the CS500 headset. This helps users respond without needing to handle the connected iPhone directly.

Designed for CS500 and CS500 XD Systems

Manufacturer compatibility guidance identifies the CS500 and CS500 XD Series as the supported wireless headset platforms. Documented CS500 examples include the CS510, CS520, CS530 and CS540, but the exact headset model should still be checked before purchase.

Direct 3.5 mm Connection

The cable requires an Apple iPhone with a built-in 3.5 mm headset socket. It is not a Lightning or USB-C accessory, and operation through a separate port adapter has not been confirmed by the manufacturer documentation used for this listing.

Optional Online Indicator Support

The API-28 is described as compatible with selected Plantronics Online Indicator or busy-light accessories. Any indicator, splitter or associated adapter is optional and is not included unless specifically stated by the seller.

Important Legacy Compatibility

The documented phone list covers the iPhone 4, 4S, 5, 5C, 5S, 6 and 6 Plus. Compatibility should not be assumed for other iPhone generations simply because they use an Apple operating system or can accept a third-party audio adapter.

Key Features:

• Connects selected Apple iPhones to compatible CS500 wireless headset systems.
• Uses the iPhone’s built-in 3.5 mm headset socket.
• Allows supported incoming mobile calls to be answered from the headset.
• Designed for Poly/Plantronics CS500 and CS500 XD Series base stations.
• Supports compatible optional Plantronics Online Indicator accessories.
• Provides a wired interface between the mobile phone and wireless headset base.

Compatibility Information:

Technical Specifications:

Connect a confirmed 3.5 mm-equipped iPhone to a compatible CS500 wireless headset system with the Poly API-28.