I don't know how installing telnet would solve your problem. I also don't know what "on my side" means.
There are plenty of ways to determine whether a username is valid without enabling telnet into your server.
ok, let me try to explain my motivation for using telnet:
I am developing web-based applications for my company which is to be made available over the internet for fellow employees working out of country. For reasons specified by management i was instructed to create a simple login script to ensure only our employees have access and that only employees who have accounts on the SME may log in.
I basically want to have the employees use their SME usernames and passowrds to be able to log in, rather than make a new database and have the trouble of 'registering' every employee again in my database and code.
I was informed i could pass the employee-provided username and password and use them in a telnet command to the SME to check if they are valid users. Thus, if the script determines that the username and password can login to the SME via telnet command then they are legitimate users and must get access.
This is only my initial idea,the only one i have so far! ^^ But by testing this i will learn if applicable and if not i should be able to then determine other means with my new found knowledge.
If there are existing means by which i can do what i would like to do then please give me some information so i may research it and try it!

again, thank you!