Having permission to view the presence status of a person is called subscribing to his presence. Presence subscription between two persons can be asymmetric. Subscription state is shown in the roster display by arrows (see Customizing the roster buffer). A left-pointing arrow means that the contact can see your presence (“from”). A right-pointing arrow means that you can see the contact's presence (“to”). The most common case is mutual subscription, a double-ended arrow (“both”).
When jabber.el receives a presence subscription request, it will present it to you in a chat buffer, and offer you to choose subscription mode and send a subscription request back to that person. The “Mutual” button accepts the request and sends a reciprocal request.1 The “One-way” button accepts the request, but doesn't ask for a subscription in return. The “Decline” button declines the request.
To request subscription to someone, type M-x
jabber-send-subscription-request. You will be prompted for the JID
to send it to. This command can also be accessed through the Roster
menu, by typing C-c C-r in the roster buffer. After that, you
will probably want to give the contact a more readable name. The
command for that is
jabber-roster-change, which is also
available in the Roster menu or by typing e on a person in the
 If this request is superfluous, the server will drop it without bothering the contact.