I was able to get a header inserted to my service using a winform with the following code
using (OperationContextScope scope = new OperationContextScope(proxy.InnerChannel))
MessageHeader header = MessageHeader.CreateHeader("DeviceIDHeader", "urn:service/mobile/endpoint/DeviceIDHeader", "12345");
but it does not work in mobile. How to do send headers to the service? I only need to send a string.