[Sable] Briain:
GSM base site registration problems with Orange SIM

Hi Aavatar, Hi Keyx

I thought the below might interest you:

I've just tried WM6.5 21234 and it works very well. It's great that you both do all this work and make these builds available to all of us; thank you very much! One thing I noticed is that a bug which was evident on the original iPAQ firmware seems to have returned in WM6.5 21234. The bug seemed to be cured (or at lease occurred less often) with the recent iPAQ WM6 build (sp40097). I've not tried any of the other WM6.5 builds to see if they can resolve this problem; I thought I'd raise it here to see if either of you were aware of it first.

It seems that the bug only manifests itself with an Orange SIM. It looks like when you are in a poor coverage area and the phone looses its GSM signal, it maybe looks for a UMTS signal and upon not finding one, it doesn’t then drop back to looking for a GSM signal. The trouble is that with an Orange SIM, there are no options to deselect UMTS (3G) and thus force the iPAQ to only look for GSM sites. Apparently, with other MNO’s settings there is an option to select GSM as the default service.

Below is a post I’ve put on the HP iPAQ forum; does anyone here have any ideas about this issue and whether a fix can be added to the WM6.5 builds?

Hi

I got a response from the electronic support request: they are based in North America and cannot help me. They propose I call the support number for the UK. In the interim, I’ve performed a few more experiments to see if I can narrow things down a bit.

I tried a WM6.5 build from the xda-developers forum and it was exactly the same as the initial HP build (you could guarantee that it wouldn’t reconnect to a GSM site after a signal loss). I then put sp40097 back on (to restore the official HP iPAQ build of WM6) and the problem seems to have gone away. It will need more testing to confirm that it's not going to appear again though; I just put the sp40097 build on this morning.

The GSM standard is for the SIM to hold a database of the strongest 4 base sites (this is part of how the handover is initiated when you move between sites; it looks to this table to decide on the next site then initiates a handover with it). I wonder if the problem is that after a dropout, the iPAQ is looking for a UMTS (there isn't one nearby) and simply not falling back to the listed GSM ones or searching for a new GSM one?

Curiously, with WM6.5, it doesn't search at all after a dropout but you can tell it to look for a site. When you do, it sometimes registers onto a GSM base site but other times searches indefinitely. I’ll live with the official HP build (sp40097) for a couple of weeks then report back here.

Incidentally, for anyone wishing to force a dropout, simply put the phone in a screened box for a few minutes then remove it and see if it re-registers itself to a GSM site. If you’re in a good area, it will probably be okay as it will see a UMTS site, however, if you’re in an area with only GSM coverage it should still reregister to the nearest GSM site. A useful source of screened box that most people will have to hand is a microwave oven. I should point out that though the microwave is a useful screened box, under no circumstances should you actually switch it on; if you do, your iPAQ will never connect to anything ever again!!

Bri