A data routing methodology where part of the data routing functionality is moved from a core network (CN) to a UTRAN (UMTS Terrestrial Radio Access Network) in a UMTS (Universal Mobile Telecommunication System) system when the communicating source and destination mobile equipments (ME) are residing inside that UMTS system. The separation of user data and signaling flows in such a situation decreases the load of the Iu interface between the UTRAN and the CN, thus decreasing the probability of congestion on this interface and resulting in availability of more Iu bandwidth. The signaling flow is still handled by the CN via the Iu interface, however the data flow is handled by the UTRAN via its internal Iur interface.