A communication system is provided of selecting the most approximate line from two or more connectable lines and connecting with a provider through the selected line in the mobile communication environment. The mobile device and the public phone of each phone company provide a standard wireless data communication facility, respectively. The public line pre-stores information about dial-up numbers of access points and a transmission speed of an internet provider. When the user starts the communication, the mobile device operates to obtain the most approximate access point information from each of the public phones and then dial up the most approximate access point through the public phone/line well-specified to the user.