General Query On Wireless Networking Devices.

Have a general query on wireless networking & devices.

My laptop wifi scan lists some access points that could be in vicinity that appear unsecured but you actually can not connect to them! The SSID name implies name of ISP and its properties are typical wifi connection properties e.g. SSID, Security, Radio type 802.11g etc.

Could it be coming from some devices set up by ISP for their own wireless broadband connectivity?
For wired broadband ISPs offer shared modem and equipment so that multiple customers LAN cables plug into the same. Is there a similar setup also for wireless broadband? I.e. some access point to which multiple customers hook on to.