Is it scott/tiger/infotech or scott/tiger@infotech?
If @ then that's the database alias - you're connecting in a client/server configuration and infotech is defined in $ORACLE_HOME/network/admin/tnsnames.ora.
Another way to do the same thing would be to set the environment variable TWO_TASK=infotech, then sqlplus scott/tiger would do the same thing.

If scott/tiger/infotech, no idea, never seen that syntax before, unless the password is "tiger/infotech".