Well, i prubed different IOS version to solve the busy problem that i reported in the list last week, by the way, thanks to all for your comments and help. Finally 12.0.5(T) appear to be good, but i'm not sure yet. Now i find a problem with the authentication over the radius server ( a windows 2000 advanced server running IAS), with certains modems, specially USR 56K external, the as5200 fail, if i see the logs in the radius i see something like this: User WmeTeO=erST c*YXf,4v!X+(A)[3{m^C}ear^*hLEm/a/FdP'mV?+ was denied access. Fully-Qualified-User-Name = RADIUSDOM\WmeTeO=erST c*YXf,4v!X+(A)[3{m^C}ear^*hLEm/a/FdP'mV?+ NAS-IP-Address = 172.17.101.5 NAS-Identifier = <not present> Called-Station-Identifier = 5300 Calling-Station-Identifier = <not present> Client-Friendly-Name = Cisco 5200 Client-IP-Address = 172.17.101.5 NAS-Port-Type = Async NAS-Port = 8 Policy-Name = <undetermined> Authentication-Type = <undetermined> EAP-Type = <undetermined> Reason-Code = 16 Reason = There was an authentication failure because of an unknown user name or a bad password. Look at Username !!!, it would be my human username and not that ! Thanks for any comments. Regards.