Method carried out by at least a first policy and charging rules function, hereinafter abbreviated as "first PCRF", and a second policy and charging rules function, hereinafter abbreviated as "second PCRF", the method comprising: by the first PCRF: receiving, from a policy and charging enforcement function, hereinafter abbreviated as "PCEF", a first message indicating an establishment of an Internet Protocol connectivity access network session, hereinafter abbreviated as "IP-CAN session", the first message comprising IP-CAN session data; determining first policy decision information for the IP-CAN session; causing a database accessible by the first PCRF and the second PCRF to store, in association with a session identifier, session information comprising, or representing, the IP-CAN session data and the first policy decision information; and providing, to the PCEF, the first policy decision information; by the second PCRF: receiving, from a PCRF client, a second message indicating a modification of the IP-CAN session, the second message comprising modified IP-CAN session data; obtaining or deriving from the second message the session identifier of the IP-CAN session; retrieving, from the database, the session information stored in association with the session identifier; determining second policy decision information for the IP-CAN session based on the modified IP-CAN session data and the retrieved session information; causing the database to store, in association with the session identifier, session information comprising, or representing, the modified IP-CAN session data and the second policy decision information; and providing, to at least one of the PCEF and the PCRF client, the second policy decision information. by the first PCRF: receiving, from a policy and charging enforcement function, hereinafter abbreviated as "PCEF", a first message indicating an establishment of an Internet Protocol connectivity access network session, hereinafter abbreviated as "IP-CAN session", the first message comprising IP-CAN session data; determining first policy decision information for the IP-CAN session; causing a database accessible by the first PCRF and the second PCRF to store, in association with a session identifier, session information comprising, or representing, the IP-CAN session data and the first policy decision information; and providing, to the PCEF, the first policy decision information; receiving, from a policy and charging enforcement function, hereinafter abbreviated as "PCEF", a first message indicating an establishment of an Internet Protocol connectivity access network session, hereinafter abbreviated as "IP-CAN session", the first message comprising IP-CAN session data; determining first policy decision information for the IP-CAN session; causing a database accessible by the first PCRF and the second PCRF to store, in association with a session identifier, session information comprising, or representing, the IP-CAN session data and the first policy decision information; and providing, to the PCEF, the first policy decision information; by the second PCRF: receiving, from a PCRF client, a second message indicating a modification of the IP-CAN session, the second message comprising modified IP-CAN session data; obtaining or deriving from the second message the session identifier of the IP-CAN session; retrieving, from the database, the session information stored in association with the session identifier; determining second policy decision information for the IP-CAN session based on the modified IP-CAN session data and the retrieved session information; causing the database to store, in association with the session identifier, session information comprising, or representing, the modified IP-CAN session data and the second policy decision information; and providing, to at least one of the PCEF and the PCRF client, the second policy decision information. receiving, from a PCRF client, a second message indicating a modification of the IP-CAN session, the second message comprising modified IP-CAN session data; obtaining or deriving from the second message the session identifier of the IP-CAN session; retrieving, from the database, the session information stored in association with the session identifier; determining second policy decision information for the IP-CAN session based on the modified IP-CAN session data and the retrieved session information; causing the database to store, in association with the session identifier, session information comprising, or representing, the modified IP-CAN session data and the second policy decision information; and providing, to at least one of the PCEF and the PCRF client, the second policy decision information.