Interdomain transfer method that allows seamless 3G

A method that enables the interdomain transfer (3G) seamless mobile terminals that are registered on a first own domain, and are registered in a second visited domain, when input (208) in a third domain visited again, the method comprising the steps of: a) determining (201) by the mobile terminal when entering (208) a new visited domain, if the mobile terminal gradually loses the radio signal visited domain; B) checking by the mobile terminal, if the new visited domain that enters is present in the list of public land mobile networks, PLMNs, preferred; C) the mobile terminal, trigger (202) authentication with the new visited domain to the domain of the mobile terminal itself; D) self-control, perform (203) authentication with the new domain visited; E) the new domain visited validate a service-level agreement, SLA, with self-control; F) receiving (204), in the new visited domain, from the own domain, user information of the mobile terminal; G out) out registration and authentication in the new visited domain, the mobile terminal being in said registered and authenticated in step three domains; H) the third domain, informing (205) the first domain for recording and satisfactory authentication; and I) the first domain, informing (206) the mobile terminal for registration and authentication satisfactory; J) the mobile terminal, determining whether the radio signal of the second domain is below an internal threshold and, if so, trigger (208) transfer to the third domain; and K) the operator of the first domain, negotiating (207) the resource allocation to the third domain, where the operator of the third domain allocates the necessary resources, in which step C) is carried out using a control message tools UMTS SIM application, from the mobile terminal to the mobile switching center gateway, GMSC, the first domain; wherein step I) is performed by using a control message tools UMTS SIM application from the mobile switching center Gateway, GMSC, the first domain to the mobile terminal; and wherein the control message is sent via SMS and is hidden from the second domain.