Running GSM shield without SIM card

Hi everyone,

I want to use GSM shield 2 without inserting a SIM card. I think that it is possible to connect to GSM shield but can I still use AT commands? For example can I see Shield's IMEI or cellular towers that can be connected?

Also does this model have integrated antenna? Can I use it right after I unbox it or do I have to buy external antenna.

Thanks in advance