Well, it depends on your application and connection, first your application must support background mode. Then, if the Internet connection is GRPS, CDMA or EDGE, your connection will be deleted and NSURLConnection will receive an error message if the connection is not restored with a waiting period. In 3G and WiFi, you can simultaneously receive data and voice. On LTE, all data connections are deleted, and witches see Codo's comment back to UMTS (3G)