It is possible to allow access to guest users to access the wireless network. If you want the access point to allow associations from client devices that do not specify an SSID in their configurations, you can set up a guest SSID. The access point includes the guest SSID in its beacon. The access point's default SSID, tsunami, is set to guest mode. However, to keep your network secure, you should disable the guest mode SSID on most access points. For more information on guest SSID and how this can be configured on the AP, have a look at the following URL.
http://www.cisco.com/en/US/products/hw/wireless/ps4570/products_configuration_guide_chapter09186a00802085c4.html#wp1017196
