Misery^W Fun with the Polycom 2W

polycom-2w

Our office has a number of these Polycom SoundStation 2W devices, and until last month they all worked pretty well. They’re basically a DECT version of the venerable SoundStation 2. (You can in fact throw away the Polycom base-station and replace it with a SIP enabled one and get an excellent cordless SIP conference phone). In the version of the firmware ours had you could even use two of them at once with the same base station at the same time to get better coverage for a large room.

If you know much about DECT that last statement should have you worried: how do two devices manage to get the same randomly generated private key? That question has one obvious answer.

There’s not much hardware available for playing with DECT. You could use an SDR and I’ve a goodly number of them, but I’m not aware of there being a particularly good stack. The answer is a bizarre evolutionary dead-end of wireless technology: the idea was that you got a special DECT base station, hooked it up to BRI ISDN port, put one of these or one of these

A type III (yes really) dect PC card.
A type III (yes really) DECT PC card.

in one’s PC, and then, one could surf the internet at a blazing 128 kilo-bits a second (or your could share and two could get 64 k) – all without wires. [These things come up on eBay every now and then if your’re curious, I paid €47 for one and a PCI to PCMCIA bridge to put it in]. Once you have one of these and have coaxed the Linux driver into working there’s a goodly selection of software to play with. I used dedected.

There are a few alarming things you’ll discover when you start poking the various bits of DECT hardware you own. The ones that got me were that key presses on the handset are sent en-claire even if the audio is encrypted, and if you have a plurality of manufacturer’s handsets connected to a base station it’s quite likely that your audio isn’t encrypted either.

From the research i did the Polycoms did appear to have a fixed key, but it’s rather hard to generate a known plain-text using a microphone. Fortunately they do have a mini USB port, and I was led to believe that if I upgraded I’d get encryption. Polycom provide, once one’s fought their CMS and agreed to export restrictions, the latest firmware upgrade, so this should be a simple upgrade. However this is Polycom and some caution is required.

To this end I purchased another console (the bit that looks like a Frisbee)  from eBay and applied the firmware update to it. It took a few goes, as there’s a goodly number of race conditions between windows installing drivers and upgrade waiting for a response from them but the experience was mostly painless. I then connected it to one of our base stations and it worked, but then the misery started: one by one the other consoles in the office lost contact with their base stations and refused to talk to them or register any more. Worse the option to pair with a DECT/GAP base station had disappeared from their menus. Woe. Caution had failed me. I tried giving the same new firmware update to the sick Polycoms, but without success.

The insides of the SoundStation 2W
The insides of the SoundStation 2W

Internally the 2W has a Xilinx CPLD, a TMS320 which is the main CPU and a DECT “Cordless Voice Module” SC14CVM. The TMS320, its RAM, ROM and JTAG connector are all hidden under a particularly-well-soldered-on screening can. What you can easily get at, is a small I2C EEPROM, an at24c32, that sits on the CVM. Swapping the contents of this ROM between the working and not-working consoles didn’t, however, bring any joy.

The next step was to tear apart the firmware: fortunately the firmware updater leaves this lying around in conventional formats. strings(1) on the TMS320 firmware isn’t initially rewarding until you remember that the TMS320 has 16 bit words and so you need to use the “-e l” option to strings. Looking at the output of strings there are two hidden menus in the firmware: one looks to be for test, and the other for diagnostics. It took a few minutes of finger pressing to find out how to get into them: Holding the up-arrow and star gets you into the tests menu, and holding the down-arrow and mute gets you into the diagnostics menu.

The hidden diagnostics menu
The hidden diagnostics menu

From here you have a few options: one allows to read and write values on the CVM EEPROM either in the console or the base (That explained how our rogue console managed to kick everyone else off.), another sets a country code.

The country code menu.
The country code menu.

The working Polycom had a country code of 22000205, all the others had one of 0. It appears that 0 is the default. The consoles appear to set the country code of any base stations they find to their own,  and will only pair with base stations that match their country code or have country code 0. Programming our remaining consoles with 22000205 brought them all back on line. All but one of them then took the new firmware update, and their missing options all came back.

The one that didn’t was on such an old version of the firmware that the updater wouldn’t update it. Much Googling revealed that we needed an intermediate firmware version from Polycom. Polycom only deal with resellers so that wasn’t a solution. So off came the screening cans:

 

Component Side of the Polycom SoundStation 2W
Component side.
The solder side.
Solder side.

 

My first plan was to clamp a high-ish address line of the ROM during the two seconds at boot when the bootloader CRCs the firmware image in the hope that, after noticing the image was corrupt, it would then go into a recovery mode and the update software would take it from there. When I tried, the bootloader duly noticed and did go into a please-upload-new-firmware loop. Unfortunately the firmware updater still didn’t want to play. No dice.

My second plan was to solder a header onto what looked like a standard TMS320 jtag port and see if I could make any sense of the ROM contents. Despite my best efforts nothing could get what should have been the TDO pin to budge, again, no dice.

Where the JTAG wasn't
Where the JTAG wasn’t

So that just left the third option, take the TMS320’s ROM off. (It’s an Am29LV400BB. Which tells us that the bootloader is at the beginning of the ROM.) So I did that, connected it to my TL866 programmer and read out the contents. I looked at the layout of the data. It matched what I was expecting. So I created a new ROM, by taking the bootloader from the update software and combining that with the application that I had just read from the ROM, but with one English word in the application changed, so the CRC would fail.

I tried programming the flash, but my TL866 said “No”, and that made me sad. I tried flashing the original contents of the ROM, and the TL866 said “No” again: more sadness.  After poking at the rom with a scope it appears that the TL866 doesn’t cope well with ROMs that have a BYTE# pin and thus can change between 8 and 16 bit widths. Disconnecting that line from the programmer and shorting it to VCC made the programmer happy.

The modified TL866 adapter.
The modified TL866 adapter.

However, now I realized that every other byte in the copy of the firmware I had taken was corrupt. In desperation I tried flashing the complete firmware file onto the ROM, and soldering the ROM back into the Polycom. Nothing. Not even an LED. Still no dice.

Finally, not relishing the prospect of getting another screening can off to get a good copy of the ROM from one of the other Polycoms, I realized that the firmware files had a 4 byte header giving the length of the file. Stripping that off, de-soldering the ROM, re-flashing, and re-soldering got me a Polycom that booted, but wasn’t so happy. I then re-flashed it to program in the new CVM firmware, and it worked like a charm.

Eugh

32 thoughts on “Misery^W Fun with the Polycom 2W”

  1. What i do not understood is if truth be told
    how you’re not actually much more smartly-appreciated than you might be
    now. You’re very intelligent. You already know therefore
    considerably in relation to this subject, made me in my opinion imagine it from numerous varied angles.
    Its like men and women aren’t fascinated unless it’s something to
    do with Lady gaga! Your individual stuffs excellent.
    At all times maintain it up!

  2. It’s a pity you don’t have a donate button! I’d without a doubt donate to this fantastic
    blog! I suppose for now i’ll settle for bookmarking and adding your RSS feed to
    my Google account. I look forward to fresh updates and will
    talk about this site with my Facebook group. Talk soon!

  3. It is tһe best time to mɑke some plans for thе future and
    it’s time to be happy. I’νe read thiѕ poѕt ɑnd if I could I desіre to suggest you some interesting things ߋr tips.
    Maybe you can write next articles referring to this article.
    I desire to read more things аbout іt!

  4. I have noticed you don’t monetize your page, don’t waste your traffic, you
    can earn additional bucks every month because you’ve
    got hi quality content. If you want to know
    how to make extra money, search for: Boorfe’s tips best adsense alternative

  5. Just wijsh to say your article is as astonishing.
    The clarity in your post is just nice and i can assume
    you’re an expert on this subject. Well with your permission let me
    tto grab your RSS feed to keep up to date with forthcoming
    post. Thanks a million and please carry on the rewarding
    work.

  6. Define food as well as nutrition courses that result in the continuum from
    health and nutrition services to strengthen the wellness of our populace:
    prejudgment to old age. authorizations, such as the Fda and also Has below 2%
    from: tweaked meals carbohydrate, guar gum tissue,
    molasses, corn syrup, salt benzoate (as a preservative) seasonings, caramel, sugar, paprika,
    tamarind, all-natural flavor), Cheddar Cheese (pastuerized dairy, cheese cultures, sodium, chemicals,
    annato color), Includes less than 2% of Basil,
    Afro-american epper, Cayenne pepper, Diamond Crystal Kosher Salt, Fresh Cilantro, Garlic, Jalapenos, Lime Extract, Onions,
    red, fresh. Tim Johnson on the ABC NewsNow system, Science Plan documents or even 125 terms for Emerging Science and Health and nutrition in Scientific Care documents.
    authorizations, including the Fda as well as The nourishment details demonstrates the nutrition material from firm operated cafes in the U.S.
    In some occasions franchised cafes deliver products that could vary either in nutritional
    material or even allergen existence. Tim Johnson on the ABC NewsNow system, Explore the most recent and
    also most advanced meals, drink, equipment, supply and solution answers for your institution nutrition procedure.

  7. Wonderful goods from you, man. I’veunderstand your stuff previous to and you
    are just extremely wonderful. I actually like what you have acquired
    here, certainly like what you’re stating and the way in which yoou saay it.
    You make it enjoyable and you still take care of to keep itt wise.
    I cant wait to read far more from you. This is actually a tremendous site.

  8. great issues altogether, you simply gained a brand new
    reader. What would you suggest about your publish that you made some days in the past?

    Any sure?

  9. I’m really loving the theme/design of your blog.

    Do you ever run into any web browser compatibility issues?
    A few of my blog visitors have complained about
    my blog not operating correctly in Explorer but looks great in Firefox.

    Do you have any advice to help fix this issue?

  10. you’re actually a excellent webmaster. The website loading
    velocity is amazing. It seems that you’re doing any distinctive trick.
    Moreover, The contents are masterwork. you have done a excellent process on this
    matter!

  11. Michelle Williams in Herve Leger: To say the Herve Leger bandage dress is passé could be
    an understatement, however by some means this explicit one is so gripping (no pun meant).
    The olive hue, key-gap lower-out and long hemline
    take a refreshing approach to an typically tried development.
    Bravo, Michelle.

  12. Heya this is somewhat of off topic but I was wondering if blogs use WYSIWYG editors or if you have to manually code with HTML.
    I’m starting a blog soon but have no coding experience so I wanted
    to get guidance from someone with experience.

    Any help would be enormously appreciated!

  13. Hello, Excellent post, Have one question are you familiar with the EHS Electronic hookup Switch communication for Polycom Phones?, I couldn’t detect the serial protocol on this devices

  14. “Fast among the young as well as passionate,Inch affirms Professor Professor of human the field of biology with Stanford School They Lun Te, whenever a person in excess of twenty years old, it is possible to be able to a crescendo throughout 2-5 min’s following a commence; along with the partner can also heat up. But earlier work shows that sperm that’s less hurt plus much more movable carries a superior possibility of resulting in a fit baby. However, she has discovered a technique (you will discover minutes from now) that enable him to absolve his problem of premature ejaculation, and last during intercourse so long as he wanted.

  15. Thanks a lot for sharing this with all folks you really
    realize what you’re talking approximately! Bookmarked.
    Kindly also discuss with my website =). We can have a link exchange agreement
    between us

  16. Oh my goodness! Impressive article dude! Many thanks,
    However I am having issues with your RSS. I don’t know why I am unable to join it.
    Is there anybody having the same RSS issues? Anybody
    who knows the solution can you kindly respond? Thanks!!

  17. Wow Thanks for this information i find it hard to discover decent answers out there when it comes to this subject material appreciate for the site website

Leave a Reply

Your email address will not be published. Required fields are marked *