Are all SIM cards created equal?

[Different Drummer]

I recently bought a cell phone (LG) online that is on the AT&T network. After I had finished charging the phone, I turned it on and received the following message:

SIM not provisioned MM #2

I contacted the company from which I ordered the phone and was told they sell only phones and that I would have to contact AT&T about getting a SIM card and getting the card activated. I don't want to make a mistake with this, so my question is, are all SIM cards created equal or would I have to get a specific type of SIM card? Thanks for any advice!

[getagrip_already]

1. the lat time I did this...

ATT just gave me a new sim card. It was a company phone on an att service plan but the sim had that error.

They just programmed a new one and all was good.

[Kali]

2. whe I buy used phones on line, I either have to use an existing card from a phone on the account or

call Verizon and they send a new one (free). is that what you mean?

[Different Drummer]

3. Yes.

Thanks for your help!