The image shows the notification service interfaces and supported service types and where each fits in the three main tiers from left to right. A) The Client Tier shows a desktop computer with an arrow labeled Web Services Interface and a desktop computer with an arrow labeled Java Interface connecting to a box entitled Notification Service. B) The Middle Tier shows a two-way arrow labeled SMTP IMAP/POP, connecting from Notification Service to a CPU labeled E-mail Server. A second arrow labeled SOAP call connects Notification Service to a CPU labeled Oracle Application Server Wireless Server. C) The Infrastructure Tier shows three arrows connecting Oracle Application Server Wireless Server to three icons respectively as follows: Fax Server, SMS Server, and Voice Gateway (represented by a cell phone).