All credits go to @Abuse for his list here, I've only added the last 2.
public enum LoginResponseCode {
UNEXPECTED_SERVER_RESPONSE(1),
INVALID_ACCOUNT_CREDENTIALS(3),
ACCOUNT_DISABLED(4),
ACCOUNT_ALREADY_LOGGED_IN(5),
RUNESCAPE_HAS_BEEN_UPDATED(6),
WORLD_IS_FULL(7),
LOGIN_SERVER_OFFLINE(8),
LOGIN_LIMIT_EXCEEDED(9),
BAD_SESSION_ID(10),
SUSPECTED_STOLEN_PASSWORD(11),
NEED_MEMBERS_FOR_THIS_WORLD(12),
COULD_NOT_COMPLETE_LOGIN_TRY_DIFFERENT_WORLD(13),
SERVER_IS_BEING_UPDATED(14),
BAD_SERVER_RESPONSE(15),
TOO_MANY_INCORRECT_LOGIN_ATTEMPTS(16),
STANDING_IN_MEMBERS_ONLY_AREA(17),
ACCOUNT_LOCKED(18),
CLOSED_BETA_WORLD(19),
INVALID_LOGINSERVER_REQUEST(20),
PROFLE_TRANSFER(21),
MALFORMED_LOGIN_PACKET(22),
NO_REPLY_FROM_LOGINSERVER(23),
ERROR_LOADING_PROFILE(24),
UNEXPECTED_LOGINSERVER_RESPONSE(25),
BLOCKED_COMPUTER(26),
SERVICE_UNAVAILABLE(27),
BILLING_ISSUES(32),
AUTHENTICATOR(56);
private final int responseCode;
LoginResponseCode(final int responseCode) {
this.responseCode = responseCode;
}
}