iPhone 3G's SIM Card in another Phone---Will it work?

yes, of course, it is possible...
also, if you're not using it with iphone for a long time you can turn off your data plan ($30/month) or change it to a cheaper one

Its a crapshoot whether it works or not.

I put my ATT iPhone sim in a Razr and it just immediately shut down.

If the specified sim is compatible it might work, but who knows that for sure?

Is the Razr locked to a different service provider?

Your sim will work in any phone locked to the same network or any phone that has been un-locked. End of story.

Sorry, that's just not true.

Not all phones even use the same model of sim. There are physical
Differences in sims.

Further, some of us have tried, and had phones (never locked ones)
shut down, and fail to work, yet you make this sweeping pronouncement?

icebike wrote:
Sorry, that's just not true.

Not all phones even use the same model of sim. There are physical
Differences in sims.

Further, some of us have tried, and had phones (never locked ones)
shut down, and fail to work, yet you make this sweeping pronouncement?

Actually for the UK (where the poster lives) it is 100% true.
In the UK all SIMs are identical.

I would like more info regarding this too.

I thought the SIM card was a standard. I see people buy unlocked phones and run them on any carrier as long as the frequency is supported.

I have never heard of physical differences. Do you have any documentation that supports this?

As mentioned above, in EU and UK, people play musical SIM all the time. Prepaid SIMs are cheap and there are at dozens of companies selling them all over EU. The only requirement is an unlocked GSM phone.

I would like more info regarding this too. I thought the SIM card was a standard.

The great thing about standards is there are so many to choose from.

Jeez, I was hoping to get another back-up phone (I was set on buy the RAZR) from ATT Pay As You Go. So now this doesn't work. I need an ATT chaep back-up phone for when I go hiking.