To face the huge demand on mobile traffic, ISPs are looking to offload traffic of their Radio Access Network to WLAN. Currently I-WLAN is the proposed offload architecture by 3GPP which tunnels the traffic to a Security Gateway. This paper proposes for ISPs an ISP Offload Infrastructure which minimizes the infrastructure cost deployment, and which can be deployed in a very short term. The ISP Offload Infrastructure classifies the EU traffic into 3 distinct classes and assigns each class a specific and adapted offload architecture: ForWarD Architecture (FWDA), Offload Service Architecture (OSA) and Offload Access Architecture (OAA). This paper shows how to deploy each Offload Architecture by using SCTP in conjunction to MOBIKE(-X) or only MOBIKE(-X). Then we measure how each Offload Architecture may affect the EU experience, and provide recommendations on how to deploy and implement the ISP Offload Infrastructure.