wpa supplicant EAP-SIM configuration

[Vincent Maurin]

Hello,

I want to connect to an access point with EAP-SIM authentication. In the 
default wpa_supplicant.conf, there is an example :

# EAP-SIM with a GSM SIM or USIM
network={
    ssid="eap-sim-test"
    key_mgmt=WPA-EAP
    eap=SIM
    pin="1234"
    pcsc=""
}

EAP usually requires an identity, but there is no "identity" field. Have 
I to set the identity ? Which value (sim card number) ?
Why does wpa supplicant need the pin code ? Does he get some information 
in the card ?
I configure also the AP side, with hostap and freeradius, so I can 
change some settings (but server configuration is hard to understand to).

Best regards,

Vincent