When the Telnet protocol is used in a client/server situation, the server SHOULD initiate negotiation of the terminal interaction mode it expects.
The Telnet protocol was defined to be perfectly symmetrical, but its application is generally asymmetric. Remote login has been known to fail because NEITHER side initiated negotiation of the required non-default terminal modes. It is generally the server that determines the preferred mode, so the server needs to initiate the negotiation; since the negotiation is symmetric, the user can also initiate it.
A client (User Telnet) SHOULD provide a means for users to enable and disable the initiation of option negotiation.
A user sometimes needs to connect to an application service (e.g., FTP or SMTP) that uses Telnet for its control stream but does not support Telnet options. User Telnet may be used for this purpose if initiation of option negotiation is disabled.