The steps and the data amount are reduced by using a PPP non-standard message to shorten a time needed for call setting, and even when a terminal or PDSN is not adapted to the non-standard message, a call setting procedure can be continued according to a PPP standard procedure. The procedure contains the steps of: establishing a wireless link between MS and PDSN, transmitting PPP standard LCP Cfg-Request from PDSN to MS, transmitting PPP non-standard AltPPP Cfg-Request from PDSN to MS, responding to AltPPP Cfg-Request and returning non-standard AltPPP Cfg-Response if MS is adapted to the non-standard message while responding to LCP Cfg-Request and returning standard LCP Cfg-Response if MS is not adapted to the non-standard message, and authenticating MS on the basis of the standard or non-standard Cfg-Response by PDSN.