score:4
Your information is correct, quoting the requirements for free Wifi here -
Smart Phone/other devices with an Active SIM card
- Turn ON Wi-Fi on your device Latch on to the Tata Docomo Wi-Fi SSID
- Click on the internet browser Fill in the details, name, mobile number, E-Mail Id
- You will receive the Serial number & PIN through SMS on the Mobile number provided by you
- Enter the Serial Number and PIN on the screen to start browsing
I can confirm that this works for US phone numbers as well, but do note that this works on 1 device only(that device needn't be the device which received the SMS). Most unlocked phones allow you to tether your Cellular Network via Wifi but not the Wifi network. So you will not be able to use this for everyone in the group.
My wife has Verizon postpaid whereas I have a Cheap Prepaid which doesn't offer any roaming. We used her's to get the code to get free Wifi, she also has Google Voice (VOIP which works after you have Wifi) and we used the second code on that to get my phone access. You could use a strategy like this to get everyone in the group free Wifi.