is implemented on a mobile phone or mobile terminal 18 wants to register at a xmpp server 3 which is associated to the msc s of a mobile communication network it is not necessary that the mobile terminal is cs associated to this network to register the xmpp client 132 at the xmpp server 3 the client 132 has to construct an identity which is called the jabber identity the jabber id looks like the following u201c user jabberserver tld device u201d the term u201c user u201d identifies the user of this service u201c jabberserver u201d refers to the domain name of the xmpp server 3 and u201c device u201d represents the actual device the user is using for the registration request the term u201c tld u201d stands for a top level domain which could be a com or de domain or any other known domain a user may have several parallel registrations via different devices or different xmpp client instances on the same device to construct the jabber id the xmpp client 132 could use information from the sim card of the mobile phone 18 the subscriber identity module sim card contains e g the msisdn number or the imsi which can be user by the xmpp client 132 to construct a u201c user u201d for the jabber id the.