Plantronics CS540 Wireless Headset

You're on a call and the printer jams three rows over, or someone at the next desk needs a signature. The CS540 is a DECT headset for exactly that minute: stand up, keep talking, deal with it. It's the convertible model in Poly's CS500 line, so one headset covers three wearing styles (over-the-head band, over-the-ear loop, or a behind-the-neck band sold separately), and at 21 grams most people forget they still have it on.

The first decision is whether your desk phone is a Cisco.

• Standard connects to most single- and multi-line corded desk phones over a universal RJ9 cable, including Avaya, Polycom, NEC and Mitel.
• Cisco IP Phone Compatible (CS540-CIS) is the same hardware, tested against Cisco's 6900, 7900, 8800, 8900, 9900 and SPA series and shipping with the Cisco EHS cable.

CS540 remote answering: HL10 lifter or EHS cable

This is the decision people miss. Out of the box the CS540 answers from a button on the headset with the handset still in its cradle, which covers most desks. Having the phone itself pick up while you're across the room needs one of two things, and neither is in the box.

• An HL10 handset lifter, a small motorized arm that physically lifts the handset. It works with nearly any desk phone, including ones too old to have an electronic headset port, which is why it's the safe answer when nobody can tell you the phone model.
• An EHS cable, which has no moving parts and is tidier on the desk, but only works if the phone supports electronic hookswitch. The cable is chosen for the phone, not the headset, so Cisco, Avaya, Polycom, Yealink and NEC each take a different one.

Tell us the phone model and we'll tell you which one it takes. That's a shorter conversation than a return.

CS540 range and battery life

The CS540 is rated up to 350 feet of roaming range and up to 7 hours of talk time, running DECT 6.0 on the 1.9GHz band. That band is reserved for voice in North America, so the headset isn't competing with your Wi-Fi for air. A full charge takes about 90 minutes, and 30 minutes on the cradle buys roughly 2 more hours if you get caught short. The battery is user-replaceable, and Poly's guidance is to swap it at 3 years or 300 charge cycles.

Is the Plantronics CS540 Bluetooth?

No. The CS540 is a DECT headset, so it doesn't pair to a laptop or a mobile over Bluetooth. It talks to its own base station, and the base plugs into your desk phone. Nothing to pair, and nothing that forgets your headset overnight.

Taking softphone calls on a computer needs the APU-76 USB adapter, and the base handles one device at a time, so that replaces the desk phone connection rather than joining it. If moving between a softphone and a desk phone all day is the actual job, a Savi model built to hold both at once is the better buy, and you can compare them in wireless headsets.