Slim chance anyone will know the answer to this but...

I'm going back to the UK for Christmas (yey) and am taking my Softbank keitai with me as it will work over there. Last time I went home it cost me a fortune on my phone bill for just the odd phone call, message etc when arranging to meet friends.

So, I was thinking of just getting a UK sim card and putting that in my phone. Questions is:

Is my phone locked to one network?

It's technically an old vodafone phone (I haven't upgraded since they changed) so I would like to think a uk vodafone sim would work. I had a surf around Google but came up blank.

Anyone got any experiences?

I have a vodafone v604t, and there's no sim card slot.
I'm pretty sure the majority of Handsets have the sim built into it somewhere. It depends if your phone has the sim card slot or not, I think it's possible to unlock some phones, but I'm sure it would be a painstaking ordeal.

(EDIT: I misread your question, sorry.)

I'm pretty sure all Japanese phones are locked-- it's only in the last couple of years they introduced phone # portability.

I know mine has a SIM card as I put it in when I first got the phone (and I just checked!). I remember trying my old UK sim card, but that didn't work. Either because it was a different network, or because it wasn't a 3G card.

I guess I'll have to just try some when I get back. I'd like to think that even if it's locked, then vodafone cards would still be ok :|

I really doubt you'll have much luck with it. GSM was never used in Japan (thus really no SIM-cards). They had their own systems and phones which are today upgraded to the 3'rd generation systems that can function in the European networks but the whole philosophy is still different.

Was it really a "SIM" -card slot?


Anyway, this is just my impression on this.
Prove me wrong! =)

Well.. It seems I was wrong. It seems that you really should be able to insert a European SIM in a Japanese Vodafone phone..

http://eurotechnology.com/3G/

I had some cheap softbank phone while in Japan and it didn't have any SIM-slot but I don't think it was a 3G-phone anyway..

are there any for sale on ebay.co.uk. 0 supply will probably tell you it aint happening.

Well I can report that it did work. At first the phone complained that it was network locked, but some research online found a code which disabled that allowing me to use a UK O2 sim card in the phone. I got full functionality, including MMS messaging and WAP internet, although they both had to be done manually, but creating new conections and entering the details.

I think I was lucky though. I was going to change my phone around now, but am now leaving Japan in March so no point. Anyways, when researching a new phone I discovered that even though most modern Japanese phones are 3G and use sim cards, the firmware on them is not written in a way which allows unlocking. I think this stems from:
1) Japanese phones are only ever available on one network. It's not like in Europe when phone companies make phones, and networks create custom firmwares to brand them. In Japan it seems that networks send out specifications for new phones and the phone companies have to design their phones to match. For example the new Docomo 905 series all have 3" screens with a minimum resolution and a multitude of other things. This means that Japanese phones aren't unlockable (generally).
2) A law was passed in Japan a few years ago that made the selling of a phone without somekind of network contract illegal. This was an attempt to cut down on phone crime (I think things like harrassment by phone call/message etc). This means that there is no second-hand phone market in Japan.

As to why I was able to unlock my phone? Mine is a Samsung, which is a Korean company. I believe my phone was their first foray into the Japanese market. They also sell the same basic phone under a different name elsewhere in the world. So, they have unlock codes.
The only other way to get a Japanese phone 'unlocked' is to flash the firmware with either a different or hacked firmware. Normally this doesn't work perfectly and you end up with reduced functionality.

I really wanted the new Docomo SO905iCS as well