TreoCentral's Douglas Morse reviews the Plantronics Discovery 640 bluetooth headset.

Read on for the full review.

First, a hearty welcome to all you new Treo owners. Many of you are still learning and playing with your new 650s from the Holidays; others have joined the Treo cult with a brand new 700w. I’ve been writing reviews since the site was called Visor Central. If you want a teary-eyed trip down memory lane, check out

It’s always fun and often amusing to read about the vintage hardware, software, and especially predictions from bygone days about the Visor Deluxe and Pocket PC. It makes for fascinating reading.

We’ve been busy writing Treo accessory reviews for a long time and I’d encourage you, to take time to read the reviews before plunking down the green stuff for accessories. In one, I failed to mention that the cross piece on a case rode a bit too low and skimmed the keyboard, and the folks in the forums let me know their displeasure. But I wiped off the tar and feathers, and since then, I’ve tried not to miss the small details. I’d encourage you to make your way to the forums if you haven’t already. Users post reviews, debate the best case to get, (or almost anything), and find special deals and promotions. If you don’t know about the Palm Pays Back promotion, do a search in the forums, and it’s right on the front page of too.

Make liberal use of the search feature in the forums, especially before asking a question. And enjoy the community that’s here and especially postings from GFunk, Lady Treo, shadowmite, and many, other regulars. There’s a ton of good information in the forums. Don’t be shy about diving in with your own questions. Remember, the only stupid questions are the ones that are never asked.

Keep this I mind too - here at the review center, we keep an arms length from the goings on at the Treo Central Store. We calls ‘em like we sees ‘em. This gives us the freedom to slam items we think are inadequate or inferior and to praise those we think you can’t do without. The Plantronics 640 Bluetooth headset may well fall into the latter group.


The Plantronics Discovery 640 Bluetooth headset is lightweight (less than an ounce) and small (about an inch long). The earpiece gel rests snuggly in your ear – on the opposite side is the ubiquitous multi-function button with a circular LED status indicator. On the body of the unit are the volume buttons on opposite ends of a pivot switch

What’s striking about the 640 is the cool metallic spy-style case in which it comes. Opening up this clamshell box you’re treated to a lot of goodies.

The ear loop is useful if you’re an active person. Otherwise, you can skip this option because there are THREE included soft gel ear tips: small, medium, and large. Choosing the right one will nicely stabilize the headset, and we don’t all have the same size and shape ears.

I admit to being rough on equipment. I don’t always read the manuals when I should and often resort to pulling and pushing when something won’t budge. Exhibit “A” is my manhandling of one of the ear gels. Instead of turning it to insert and remove it from the “neutral” position as the manual instructs, I yanked it at an odd position and slightly damaged the connectors. Learn from my mistake. Read the manual, which is clearly written. Like many accessory manuals, it’s available here on Treo Central.

I caution you – it’s easy to spend hundreds of dollars on accessories, many of which are not quite right for you. Reading the reviews, forums, and manuals prior to purchase will be a worthwhile investment of time that’ll really pay off in satisfaction with those products you do buy.

Back to the 640. The case has a slot for the earpiece itself. The charging sleeve slides over the earpiece barely adding any bulk to it.. One way to charge the Discovery 640 is to plug the AC adapter into the bottom of the cylindrical sleeve. The unit ships with four different adapters for the bottom of the charging tube. These allow the charger to be used with AC adapters from Nokia, Sony Ericsson, Siemens, and Motorola (not Treo though) obviating the need for the included AC adapter.

Even more intriguing is the battery holder that plugs into the bottom of the charging unit for charging with an AAA battery.


Before first use, the headset needs charging for a minimum of an hour and it takes about three hours to fully charge. One AAA battery will charge the headset for about 15 hours of talk time. Not too shabby! Of all of the headsets I’ve played with, this is the only one with this extraordinary feature. I’m totally knocked out by the attention given to power use and convenience with this baby. Even when just turning the power on by holding the call control button, the LED will flash red three times to indicate a full charge, twice for a moderate charge, or once when the battery has less than 1/3rd charge left.

Pairing with your Treo is easy. Hold down the multifunction button until the LED flashes blue and red. With the Treo in discovery mode, pairing will be a cinch since you enter the easy to remember “0000” pass code.

This headset also supports multipoint. What’s that? Glad you asked. It means the headset can be used with two different Bluetooth devices. If you initiate a call with one phone, the headset will use that one. It will also pick up from either headset. Although the Treo 650 doesn’t natively support it, the headset does support voice activated dialing.

Not only does the status LED give you a ballpark idea of charge level when you power on, but infrequent flashing of red and blue indicates a missed call. Pressing any button cancels this.

The storage case looks great and holds a whole host of accessories. However, it may be a bit much, as you generally don’t need to carry two extra ear adapters and four small circular charging adapters, but at the very least, it provides home to store all these small items together, instead of trying to remember where you put this or that piece. Sort of like a power drill bit or socket wrench case. Neat and tidy. A thoughtful touch on Plantronics’ part.

Unfortunately, the AC adapter (which is reasonably sized) doesn’t fit in the case. The case, then, may sit at home, leaving you looking for a solution of finding something else to tote the accessories you do need such as the battery adapter, AC adapter, and ear loop. Perhaps a small pouch would do the trick, but the battery charger/sleeve does have a ball point pen type shape and a clasp to clip on a shirt pocket.

Optional accessories include a 12v DC car charger, USB charger, and a Mini-USB adapter for use with the Motorola RAZR charger.

Warranty is one year but credit cards will extend the warranty for another year. If you’re going to be making many electronics purchases in the near future, I’d suggest checking into your card member agreement and start a file of receipts.

So much for the physical layout of the 640. How about sound quality, which is, after all, the meat and potatoes of any headset. It’s good. Not exceptional, not terrible either. You might experience the usual problems with scratchy sound, minor drop outs and the like under some circumstances, as I did. I’d love to know if Bluetooth 1.2 makes a significant difference in sound quality compared to Bluetooth 1.1 and when I get my mitts on a new 700w I’ll be able to give you some comparison test results.


An excellent, lightweight headset with a lot power options, nice form factor, and a slick case that could be better. The 640 is usable with many phones’ AC adapters and even an AAA battery, which you can buy anywhere. The sound quality is solid, though not exceptional. It rates it an excellent value in my book.

Ratings (out of 5)

  • Design: 5
  • Usability: 5
  • Sound Quality: 4
  • Cost/Benefit: 5

Overall: 5


  • Super-lightweight
  • Great charging options
  • Three sizes of earpieces


  • Case needs some re-thinking
  • Sound quality just okay

(First posted at TreoCentral on Jan 23, 2006