I need Operating system name of WIndows remote system which is using native telnet.

HI My project have set of remote system which are connected under one gateway, after login to gateway we connect to end customer remote system through telnet or ftp, in this case this system has native telnet which is windows 7(as i came to know when we tried investigating this system), I am trying to capture OS name of remote system, Systeminfo, ver and telnet commands are not working as it is using Native telnet. Please help me is there a way to capture OS name. I can't change anything on end system which is secured by Hospital network. Our ultimate goal is to establish telnet connection to this gateway which we are using applet to connect telnet window on my application. I am looking for options to find OS name either by perl script or any other manner