an e-mail address. Figure 4-16 Bob's terminal Do you think I should implements both pack my coat for our vacation? SIP and HTTP. The Internet Let me check the weather forecast on the Internet Chapter 4 This way Bob can configure his SIP redirect server to send incoming voice sessions to his e-mail account. The server obliges by returning mailto:Bob.Johnson@company.com in response to a SIP request (Fig- ure 4-17). Laura, who's notoriously impatient, can choose between leaving Bob a voice mail or writing him an e-mail. If Bob has redirected incoming sessions on his Web page, she can amuse herself by looking at pictures of his new puppy, car, or house while her call is in a queue. Web pages can also include SIP URLs besides e-mail addresses, provid- ing click-to-dial features. Having a SIP URL that can be redirected to any other means of commu- nication considerably reduces the amount of different contact information needed by an individual. Currently, an average business card contains at least a fixed phone number, a mobile number, a fax number, and an e-mail address (Figure 4-18). SIP distills all this to a single URL. Users will contact our SIP server specifying what type of service (voice call, e-mail, fax) they want, and our redirect server will provide them with the proper URL. Same Routing Concept as SMTP SIP messages are routed in much the same way as e-mail messages. They can also carry multipart message bodies using Multipurpose Internet Mail Extensions (MIME) [RFC 2045]. However, SIP is not good at transporting large amounts of data; it's just not designed as a transport protocol. Figure 4-17 I'd rather drop Laura can choose him an e-mail between leaving a voice mail or Laura SIP proxy sending an e-mail. (1) Invitation to a session for SIP: Bob.Johnson@company.com (2) You better try: mailto: Bob.Johnson@company.com SIP: Bob.VoiceMail@company.com E-mail (mailto: Bob.Johnson@company.com) The Session Initiation Protocol: SIP Figure 4-18 Bob Johnson Bob Johnson Bob has a SIP Telephone: +1 212 555 5555 busines