3G Roaming – Pleasure with Pitfalls

Thanks to an international 3G subscription I have long ago given up searching for Wifi hotspots at the locations I travel to. Instead, as the Sprint guys put it, the 3G network is following me wherever I go. I see it the other way round. Wherever I go, the network is already there. While I have always managed so far to find good 3G or EDGE connectivity, there are some pitfalls which I wouldn’t have thought existed anymore three years after the commercial launch of the first UMTS networks. Here are some strange but true examples:

France: For a month or two now, Orange, the mobile operator that allows me to roam to its 3G network, seems to have a new software version running on their UMTS network in Paris. Since then, my almost brand new Nokia N70 behaves strangely and has trouble establishing a dedicated bearer during a packet session after some time of inactivity. This results in very long delays in the order of 10 seconds or more when I click on a link after some time of network inactivity. The only remedy is to trick the network into letting me have a dedicated channel continuously by constantly sending pings to a host on the network. While this helps for notebook use, I can’t use this trick while web browsing via the mobile phone. So I prefer using Organe’s EDGE network by forcing the mobile into GSM only mode. In other parts of the country things work flawlessly. This is probably due to the fact that Orange uses different UMTS access vendors in different parts of the country: Alcatel in Paris, Nortel and Nokia in other parts of the country. Well done, Orange!

Germany: Here, I have a greater choice of UMTS roaming partners: T-Mobile, E-Plus and O2. The first two work flawlessly with my Nokia N70. O2 also works well if the mobile can find the UMTS network. Sometimes, however, the mobile just refuses to see the network, especially after the mobile has lost coverage for some time like for example if I have parked the car in an underground garage. Switching the phone on or off does not change anything. Even a manual network search, which shows that the 3G network is available, does not force the mobile back into O2’s UMTS network. The only action that helps sometimes is to go back to the place where the phone has no GSM or UMTS coverage of O2’s network for a minute. It’s a repeatable phenomenon and I’ve only seen it in Germany and only with O2. Also, I have to restart the phone much more often than in other networks, about once per day, as after some time I can’t connect to the Internet anymore.

Austria: Again, I have several roaming partners for UMTS: T-Mobile, A1 and One. In the A1 network I have detected the strangest problem yet. With both my Nokia N70 and my somewhat older Sony Ericsson V800 I have problems to send data from the notebook to the network. An analysis with Wireshark, a network tracing tool, revealed that the network has problems with large IP packets in uplink direction. At first I thought it was a specific mobile problem in combination with the network components used in the A1 network. However, as two completely different phones have the same problem it seems to be a general network issue. What helps is to reduce the Maximum Transfer Size (MTU) of the notebook for dial up connections. After changing the MTU size to 480 bytes as described in this Microsoft bulletin, things worked a lot better. But quite frankly, I prefer using ONE’s network where things work as they should. Just in case I ever end up in a part of Austria where ONE’s network is not available, I still have my MTU jocker ready.

All of this is very strange as both of my UMTS phones are widely used in these countries. But I think it shows that 3G interoperability is still not where it should be. Nevertheless, things are not as bad as they might seem after describing these three cases for the following reasons: Even in the countries described above I have found at least one network in which things work flawlessly with my mobiles. In addition, here’s a list of countries where I didn’t encounter problems, at least not in the networks I used: Switzerland (GPRS and EDGE), Spain, Italy, Belgium (EDGE), The Netherlands, U.K. and Portugal.