The A10 cable (a.k.a. A10-16) can be used with any H-series headset to connect directly into a phone's headset port. When the A10 cable is used, no other amplifier is required.

A10 Direct Connect Cable:
Easily connect any Plantronics H-series headset to a headset-ready phone via the headset port with A10.

Recommended for use in an environment with a mix of M22 amplifiers and direct connect solutions.*

Allows H tops to be used in amplified and direct connect systems – and reduces the risk that the wrong headset will be connected (Polaris on an M22 or H top on a U10P) which would result in degraded transmit.