1. 1 True Number Portability and Advanced Call Screening in a SIP-Based IP Telephony System Ismail Dalgic, Michael Borella, Rick Dean, Jacek Grabiec, Jerry Mahler, Guido Schuster, and Ikhlag Sidhu 3Com Corporation

2. 2 Overview vTraditional PSTN (public switched telephone network) features l CLASS (custom local area signaling service) l PBX (private branch exchange) vPDA Enhanced IP Telephony vSIP (session initiation protocol), Etherphone and SIP-EtherPhone vSystem Integration --- Number Portability

3. 3 CLASS Features vCall blocking l The customer may specify one or more numbers from which he or she does not want to receive calls vCall trace l Allows a customer to trigger a trace of the number of the most recent caller vCall return l Returns a call to the most recent caller. If the most recent caller is busy, the returned call may be queued until it can be completed

4. 4 CLASS Features vCaller ID l The caller’s number is automatically displayed vCaller ID blocking l Allows a caller to block the display of their number in a callee’s caller ID device vPriority ringing l Different priority numbers have different rings vCall forwarding l A customer may cause calls to their number to be automatically forwarded to another number for a period of time

5. 5 PBX Features vPBX is usually used within a medium-to- large-sized business for employee telephony service vCall transfer l An established call may be transferred form one number to another on the same PBX vCall forwarding l A PBX number can be programmed to automatically transfer a call to another number when the first number doesn’t answer or is busy

6. 6 PBX Features vCamp-on queuing l A call to a busy number can be queued, and the PBX will ring them when the callee answers vConference calling l Two or more parties can be connected to one another by dialing into a conference bridge number vCall parking l An established call at one number can be put on hold and reestablished from another number

7. 7 PBX Features vExecutive override l A privileged individual can break into an established call and then the call becomes three-way

8. 8 PDA Enhanced IP Telephony vTrue Portable l The PDA follows the user wherever he/she goes vShifting intelligence from the network to the telephones vProviding personal and location information to the network by user’s PDA

9. 9 New Application and Services of PDA vThe PDA may act as a smart card, providing authentication information for making toll calls vThe user may program the system through the PDA. For example, l During the business hours the default location to forward calls could be set to be the user’s office, and during other hours his/her cellular pager

10. 10 New Application and Services of PDA vDownload voicemail and play it back offline l It will be useful if the user could not spend much time on the phone l A traveler at an airport may download his/her 30 min worth of voicemail in a few min just before taking a flight, and may listen to those message during the flight

11. 11 Session Initiation Protocol (SIP) vSIP is an application-layer control protocol that can establish, modify and terminate multimedia sessions or calls vTwo major architectural elements l User agent (UA) : resides at SIP end stations » User agent client (UAC): issuing INVITE request » User agent server (UAS): accepting the call l Network server: three different types » Redirect server » Proxy server » registrar server

12. 12 SIP Network Server vRegistrar server l Used to record the SIP address (SIP URL) and the associated IP address vRedirect server l It processes an INVITE message by sending back the SIP address where the callee is reachable vProxy server l Stateful or stateless l forking or nonforking

13. 13 SIP Network Structure SIP-based station SIP-based station Registration Registrar server Main SIP Server Redirect Server (SIP database) Issuing INTIVE message Proxy server SIP-based station SIP-based station Connected

14. 14 SIP-Etherphone vEtherphone l An Etherphone is a telephone that can be plugged into an Ethernet port l Support IP using an IP address that is obtained by Dynamic Host Configuration Protocol ( DHCP) » If the location is changed, the IP address automatically changed

15. 15 SIP-Etherphone vTow major parts of Etherphone l Signaling stack » Setup phase » Manage phase » Tear down phase l Media engine » Sender: sampling and encoding the voice » Receiver: performing the reverse operations and manage a receiver buffer to compensate for network jitter vSIP-Etherphone has a serial port through which a PDA can be attached

16. 16 The SIP System Architecture Local Area Network SIP-based Etherphones at every desk, with PDA interface Main SIP server SIP database SIP-based client Data network Router office #2203 PDA office #2209 PDA (infrared, wireless) Move to (infrared, wireless) PDA

17. 17 The connection of SIP network and PSTN vPSTN/SIP gateway l The gateway provides a connection between the LAN and the PSTN l The gateway acts as a SIP UA on behalf of the PSTN phones. SIP-based LAN Regular PSTN phone Gateway

18. 18 True number portability vA caller can reach a particular person rather than a particular phone vA person authenticates himself to the SIP-Etherphone by synchronization their PDA with the SIP-Etherphone vMultiple users can register with one SIP- Etherphone by simply synchronizing one after another

19. 19 Conclusions vAdvantages l Shoppers can make purchases at a store simply by tapping a few buttons on their PDAs, and the money would be transferred from the PDA to the merchant l Shoppers can also instantaneously receive detailed information on location about the products at the store l Presenters can remotely control computer presentations using their PDAs

20. 20 Conclusions vAdvanced call screening l Making use of the address book and date book of the PDA to allow the assignment of priorities for meetings and addresses l Blocking unwanted calls l Defining the particular behavior for particular callers

21. 21 Conclusions Such new applications will bring great value by allowing mobile users to save time and money. Furthermore, users are to be more connected at any location and avoid unnecessary disturbance.