The success of Web Services, an open Internet standards based technology, opens the door to the construction of business applications in the distributed computing world. As Web Services are based on open standards, it lets the integration of different kinds of software components, including the wireless and mobile applications. However, the Post PC World, dominated by mobile devices, is not completely ready to Web Service accesss, due to memory and processing constraints. Specific architectures for an easy and clear Web Services integration are required.This article introduces the main aspects related with Web Services access from mobile devices. Two proposals are presented for high and low end mobile devices, using Java 2 Platform, Micro Edition (J2ME) Web Services API (WSA) and Short Messaging Service (SMS) respectively, which define a specific architecture for each case.