People using a Treo 680 or Centro on various networks (including T-Mobile and O2 in the UK) have recently reported an increasing amount of “dropped calls”, etc. As this has happened somewhat frequently, a network “upgrade” was a likely culprit.

A T-Mobile manager has posted the following, somewhat long-winded explanation of the issue:

Ok, I now understand the problem. I spoke with an RF Engineer about it.

There was a BTS upgrade to the system – perhaps not in all markets – but in mine, and I would assume everywhere where the problem exists…that upgrade was applied by TMobile about five weeks ago. [This also explains why some users report that the problem ceases when they travel outside of their "normal" use area. Those areas may not have base-stations by Nokia / Siemens, or perhaps don't have the same software revision that exposes the problem.]

The real issue is due to a “feature” called DTX – or Discontinue Transmission. In essense it allows either end to “discontinue” transmitting when there’s a silence. In short, the phone recognizes that you’re not talking and enters DTX mode. This means it doesn’t have to transmit on the radio during the time DTX is enabled, thus saving power. The phone is supposed to recognize when you start talking again, and signal the base station to discontinue DTX mode.

For some reason, DTX mode isn’t discontinued when you start talking again and the uplink radio traffic is either lost or doesn’t occur. Since DTX isn’t new, one would assume that it worked properly before, and that some interaction in the new base station upgrade has revealed some interoperability problems.

Normally the carrier could release updates to a phones firmware – because they would have access through the vendor. This gets into a grey area, I expect, as to what’s possible etc. But suffice it to say that I expect TMo isn’t exactly excited about spending time and money on a fix to the handset they never sold or promised to support – even if Palm would allow them to modify the firmware (which Palm might well not agree to).

Palm doesn’t want to spend any resources themselves on Palm OS when it’s dead and gone and they’re trying to get WebOS going and keep the company alive. [And I've been told as much by Palm.]

However, as I said before, this DTX problem does occur on some other handsets – ones TMo sold. Thus, they’ll want to address these handsets.

The wrinkle is this. They can address the interoperability problem in either of two ways.

1) They can update the software in the handset so it doesn’t end up in a faulty DTX mode in relation to the base-station.

2) They can pressure Nokia / Siemens (that page link above is now dead – go figure) to re-work the software in the base-station, also to improve the interoperability problem.

For those of us with Treos and Centros – the first solution will leave us out in the cold. The second has a good chance of fixing it for us.

But I don’t know how urgent TMo feels the problem is, and how they’re leaning to fix the problem. If they only have a few handsets with the problem – and they can get the problem to go away by making people upgrade etc – they’ll probably choose option 1. It would be a lot cheaper and easier I expect.

Palm probably celebrates this event as you read this – let’s see what happens…

Related posts:

  1. Palm announces Centro Smartphone – what it really is…
  2. Palm’s TouchStone hit with quality issues
  3. PSA for Austrians: A1 (and 3) have network outages
  4. BlackBerry Bold yanked due to software issues
  5. Verizon opens network; puts Treo 755p teaser page online