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					Re-Inventing the Phone
System




              Henning Schulzrinne
            Dept. of Computer Science
               Columbia University
                  (Brooklyn Poly)

Feb. 2005          Future of Telecommunications
Overview
   Predictions – some plausible outcomes
   Internet – from research dominance to consumer-
    driven
   Interconnection vs. islands
       peer-to-peer vs. server-based
   The end of phone tag?
   The future of telephone numbers
   Challenges:
       setup and configuration
       reliability
       unsolicited communications
       creating new services
       emergency services (911)


Feb. 2005             Future of Telecommunications
 Lifecycle of technologies
traditional technology propagation:


 military                corporate                   consumer

         opex/capex                capex/opex                 capex
           doesn’t                  sensitive,              sensitive;
           matter;                     but                   amateur
            expert                 amortized;
           support                    expert
                                     support


  Can it be done?          Can I afford it?          Can my mother use it?


  Feb. 2005           Future of Telecommunications
   Cause of death for the next big
   thing
                               QoS     multi-    mobile   active   IPsec IPv6
                                       cast      IP       networks
not manageable across
competing domains
                                                         
not configurable by normal
users (or apps writers)
                                                                  
no business model for ISPs
                                                                     
no initial gain
                                                                      
80% solution in existing
system
                                                                     
                                                                         (NAT)

increase system
vulnerability
                                                         


     Feb. 2005             Future of Telecommunications
     Evolution of VoIP
                                                        ―how can I make it
                                                          stop ringing?‖

long-distance calling,
      ca. 1930                ―does it do                 going beyond
                             call transfer?‖             the black phone

  ―amazing – the
                                catching up
   phone rings‖
                            with the digital PBX



  1996-2000                    2000-2003                      2004-


    Feb. 2005            Future of Telecommunications
(Early) Adulthood
   ―fully developed and mature‖
       Not quite yet, but no longer a teenager
       probably need another 6 years to be grown
        up…
   Responsibilities:
       Dealing with elderly relatives  POTS
       Financial issues  payments, RADIUS
       Family emergencies  911


Feb. 2005        Future of Telecommunications
PSTN vs. Internet Telephony
PSTN:


              Signaling & Media                 Signaling & Media


                                               China
Internet
telephony:
                  Signaling                           Signaling




                                   Media
   Belgian customer,                                              Australia
   currently visiting US


 Feb. 2005             Future of Telecommunications
Evolution: disaggregation
   All devices are nomadic
                                                                voice service provider
        new location, but same identifier




                                                     Yahoo
    
                                                                        [VSP]
   Telephone companies are no                                   (TCP, RTP, SIP)
    longer needed
       there are still carriers for DSL and                            ISP




                                                     MCI
        cable ―IP dial tone‖                                        (IP, DHCP)
       but unaware of type of data carried
        (voice, web, IM, …)
                                                                    dark fiber




                                                     NYSERNET
       VSP may be in another state or                               provider
        country                                                        (λ)
       anybody can be their own ―VSP‖
   Corporations and universities
    don’t have email carriers, either

Feb. 2005             Future of Telecommunications
Alternative evolution: duopoly
                                                       block port 25
 ILEC
 voice
            ILEC
            VoD
                   web     MSO
                           voice
                                    MSO
                                    VoD
                                           web          (email)
                                                       reduce QoS for
         ILEC                      MSO                  UDP
          ISP                      ISP                 restrictive
                                                        (symmetric) NATs
         ILEC                   MSO
         DSL                cable modem                QoS only through
                                                        application
                                                        negotiation




Feb. 2005                Future of Telecommunications
Internet evolution alternatives

                                     ISP#1

    IPv6        vs.                                    ISP#3
                                  SBC



                                     ISP#2


                                             stacked
                                             NATs




Feb. 2005   Future of Telecommunications
  Technology evolution of PSTN
100
90
80
70
60                                                   electromech
50                                                   analog
40                                                   digital
30
20
10
 0
       1980 1985 1987 1990 1995 2000 2001

           SS7: 1987-1997

      Feb. 2005       Future of Telecommunications
The end of the beginning and the
beginning of the end
   Already, most large PBX  VoIP
       but interconnect largely via PSTN
       development of digital switches has ceased
   Large fraction of international traffic VoIP
       most prepaid calling cards
   Japan: BB Phone 3.85m (4/2004)
   US: Vonage 400,000 (1/2005)
   Likely PSTN for residential/SOHO users for
    decade+
       maybe forced upgrade: residential gateway at line
        termination


Feb. 2005          Future of Telecommunications
Challenges and Opportunities
   User-visible complexity and reliability
   Will there be telephone numbers?
   Peer-to-peer vs. server-based
   Presence as service enabler
   Spam
   911
   Service creation

Feb. 2005      Future of Telecommunications
User-visible complexity
   Lots of obscure configuration parameters
       trivial mistakes cause silent failures
   NATs and firewalls
       strange failures: one-way voice, interrupted calls
   Reliability
       user has no clue whether malfunction is due to
               software/phone or operating system
               voice service provider
               Internet service provider
               Callee service provider


Feb. 2005                 Future of Telecommunications
          Does it have to be that
          complicated?




•   highly technical parameters, with differing names
•   inconsistent conventions for user and realm
•   made worse by limited end systems (configure by multi-tap)
•   usually fails with some cryptic error message and no indication which parameter
•   out-of-box experience not good
           Feb. 2005             Future of Telecommunications
NAT and VPN troubles
   Unplanned transition from
    Internet = one global address                             Internet
    space to clouds (―realms‖) of                         ?
    unknown scope
       Can’t know without help whether
        directly reachable                             home NAT

       Any number of concentric spaces                           ?
   There is no universally workable               ?          ISP NAT

    NAT solution
       always problems with inbound
        calls
       may need to maintain and refresh
        permanent connections to globally
        routable entity
       may need relay agent for media
        (TURN)
Feb. 2005           Future of Telecommunications
        Server-based vs peer-to-peer
C
    S
            C
                       Server-based
C           C              Cost: maintenance, configuration
    C
                           Central points of failures
                           Managed SIP infrastructure
                           Controlled infrastructure (e.g., DNS)
P          P
                       Peer-to-peer
P          P
                           Robust: no central dependency
    P
                           Self organizing, no configuration
                           Scalability ?


        Feb. 2005             Future of Telecommunications
Will there be telephone numbers?
   Yes:
                                                          +1 212 555 1234
       Some locality (shorter)
       Easy to convey orally
       There are lots of them…
                                                               DNS
   No:                                                       NAPTR

       Hard to keep when moving
       Becoming 10/12-digit random                 sip:bob@example.com
        number
       Already have email address
   Prediction:
       slow fade, with ENUM as bridge




Feb. 2005            Future of Telecommunications
P2P-SIP
   Differences to proprietary Skype architecture
       Robust and efficient lookup using DHT
       Interoperability
          DHT algorithm uses SIP protocol messages

       Hybrid architecture
          First try DNS NAPTR/SRV

          if no SIP server there, then lookup in SIP+P2P


   Unlike file-sharing applications
       Data storage, caching, delay, reliability
   Disadvantages
       Lookup delay and security

Feb. 2005           Future of Telecommunications
(SIP) unsolicited calls and
messages
   Possibly at least as
    large a problem as                                 mutual
    spam                                               PK authentication (TLS)
        more annoying (ring,
         pop-up)
        Bayesian content
         filtering unlikely to
         work                                      home.com
    identity-based                 Digest
    filtering
   PKI for every user
    unrealistic
   Use two-stage
    authentication
        SIP identity work




Feb. 2005               Future of Telecommunications
         Domain Classification
   Classification of domains based on their identity instantiation and
    maintenance procedures plus other domain policies.
        Admission controlled domains
             Strict identity instantiation with long term relationships
                    Example: Employees, students, bank customers
        Bonded domains
             Membership possible only through posting of bonds tied to a expected behavior
        Membership domains
             No personal verification of new members but verifiable identification required such as a
              valid credit card and/or payment
                    Example: E-bay, phone and data carriers
        Open domains
             No limit or background check on identity creation and usage
                    Example: Hotmail
        Open, rate limited domains
             Open but limits the number of messages per time unit and prevents account creation by
              bots
                    Example: Yahoo




         Feb. 2005                      Future of Telecommunications
  Reputation service
                         has sent
                                           David
              Carol
                          IM to
                                                   has sent
                                                   email to

                      Emily              Frank




                is this a spammer?
Alice                                                Bob

  Feb. 2005       Future of Telecommunications
Traditional Emergency Calling
   Basic 911: just route to local PSAP
       based on local switch
       no location delivery
   Enhanced 911: route + location delivery (90%+?)
       multiple PSAPs per PSTN switch
       multiple switches per PSAP
       location delivered out-of-band via caller number
   Phase I wireless (70%)
       call delivery based on cell tower and face
       no location delivery
   Phase II wireless (30%)
       call delivery based on geo address
       geo location delivery to PSAP



Feb. 2005             Future of Telecommunications
Core problems
   PSTN: approximate routing often works
       same switch
       based on cell tower
       based on caller number
   PSTN: relatively few, regionally-limited
    telecom providers (carriers)
   IP: carrier = bobs-bakery.com
   IP: no such approximations (usually)
       application layer (e.g., SIP) has no clue as to
        location
       L1—L3 may know about location (at least
        approximately), but don’t know about emergency
        calls
Feb. 2005          Future of Telecommunications
911: Location-based call routing
– UA knows its location

GPS



INVITE sips:sos@



48° 49' N 2° 29' E

   outbound
   proxy server




   DHCP
                     48° 49' N 2° 29' E  Paris fire department

Feb. 2005              Future of Telecommunications
Presence as communication
facilitator




Feb. 2005   Future of Telecommunications
The role of presence
     Guess-and-ring                                     Presence-based
          high probability of failure:                          facilitates unscheduled
                   ―telephone tag‖                               communications
                   inappropriate time (call during              provide recipient-specific
                    meeting)                                      information
                   inappropriate media (audio in                only contact in real-time if
                    public place)                                 destination is willing and able
          current solutions:                                    appropriately use synchronous
                   voice mail  tedious, doesn’t                 vs. asynchronous
                    scale, hard to search and
                    catalogue, no indication of                   communication
                    when call might be returned                  guide media use (text vs.
                   automated call back  rarely                  audio)
                    used, too inflexible                         predict availability in the near
           most successful calls are                            future (timed presence)
           now scheduled by email



                    Prediction: almost all (professional) communication
                        will be presence-initiated or pre-scheduled


    Feb. 2005                      Future of Telecommunications
Basic presence
   Role of presence
       initially: ―can I send an instant message and expect a
        response?‖
       now: ―should I use voice or IM? is my call going to
        interrupt a meeting?‖
   Yahoo, MSN, Skype presence services:
       on-line & off-line
           useful in modem days – but many people are (technically)
            on-line 24x7
           thus, need to provide more context
       + simple status (―not at my desk‖)
           entered manually  rarely correct
           does not provide enough context for directing interactive
            communications


Feb. 2005               Future of Telecommunications
Context-aware communication
      context = ―the interrelated conditions in
       which something exists or occurs‖
      anything known about the participants in
       the (potential) communication relationship
      both at caller and callee
time                          CPL
capabilities                  caller preferences
location                      location-based call routing
                              location events
activity/availability         presence
sensor data (mood, bio) privacy issues similar to
                        location data

Feb. 2005               Future of Telecommunications
Presence and event
notification
   Presence = special case of                  Events in multimedia
    event notification                           systems:
       ―user Alice is available for                REFER (call transfer)
        communication‖                              message waiting indication
                                                     conference floor control
    Human users:
                                                 

                                                    conference membership
       multiple contacts per                       push-to-talk
        presentity                                  system configuration
            device (cell, PDA, phone, …)
                                                 General events:
        
                                             
           service (―audio‖)
                                                    emergency alert (―reverse
       activities, current and                      911‖)
        planned
                                                    industrial sensors (―boiler
       surroundings (noise, privacy,                pressure too high‖)
        vehicle, …)                                 business events (―more than
       contact information                          20 people waiting for
       composing (typing,                           service‖)
        recording audio/video IM,
        …)
Feb. 2005                 Future of Telecommunications
IETF efforts
   SIP, SIPPING and SIMPLE working groups
       but also XCON (conferencing)
   Define SIP methods PUBLISH, SUBSCRIBE, NOTIFY
   GEOPRIV:
       geospatial privacy
       location determination via DHCP
       information delivery via SIP, HTTP, …
       privacy policies
   SIMPLE:
       architecture for events and rich presence
       configuration (XCAP)
       session-oriented IM (↔ page mode)
       filtering, rate limiting and authorization

Feb. 2005            Future of Telecommunications
                Presence data model

 person             ―calendar‖                ―cell‖                 ―manual‖
 (presentity)

(views)

                            alice@example.com           r42@example.com
services                     audio, video, text              video




devices

                Feb. 2005             Future of Telecommunications
Presence data architecture
presence sources

    PUBLISH

                                                raw
               create
                view
                                             presence                                privacy
             (compose)                       document                                filtering


                     XCAP                                       depends on watcher        XCAP
                                      select best source
                                      resolve contradictions


             composition                                                             privacy
               policy                                                                 policy

            (not defined yet)
                                                               draft-ietf-simple-presence-data-model



Feb. 2005                       Future of Telecommunications
Presence data architecture
 candidate                                           raw
 presence                     watcher             presence             post-processing
                                                                        composition
 document                      filter             document               (merging)




                                    SUBSCRIBE
        remove data not of
        interest                                difference
                                                to previous notification


                                                                         final
                                                                       presence
             watcher                                                   document
                                               NOTIFY




Feb. 2005                    Future of Telecommunications
RPID: rich presence
                      <person> <tuple>               <device>
    <activities>
    <class>
    <mood>
    <place-is>
    <place-type>
    <privacy>
    <relationship>
    <service-class>
    <sphere>
    <status-icon>
    <time-offset>
    <user-input>


Feb. 2005             Future of Telecommunications
Rich presence: time information
     Presence is currently about here and now
     but often only have (recent) past – e.g., calendar
     or future
          ―will be traveling in two hours‖
          ―will be back shortly‖
     allows watcher to plan communication

                             from             RPID             until

                                                                              time



           timed-status                                        timed-status
                                          now




    Feb. 2005                   Future of Telecommunications
Privacy rules
   Conditions                              User gets maximum of
       identity, sphere                     permissions across all
       time of day                          matching rules
       current location                        privacy-safe composition:
       identity as <uri> or                     removal of a rule can only
        <domain> + <except>                      reduce privileges
   Actions                                 Extendable to new
       watcher confirmation                 presence data
                                                 rich presence
   Transformations                          

                                                biological sensors
       include information
                                                mood sensors
       reduced accuracy




Feb. 2005             Future of Telecommunications
                <conditions>
                                  Example rules document
                                  <rule id=1>

                                   <identity><id>user@example.com</id></identity>
            <actions>




                                   <sub-handling>allow</sub-handling>
<ruleset>




                                    <provide-services>
              <transformations>




                                      <service-uri-scheme>sip</service-uri-scheme>
                                      <service-uri-scheme>mailto</service-uri-scheme>
                                    </provide-services>
                                    <provide-person>true</provide-person>
                                    <provide-activities>true</provide-activities>
                                    <provide-user-input>bare</provide-user-input>




                                  Feb. 2005           Future of Telecommunications
User service creation
   Old model:
       ―Killer application‖
       small set of applications created by experts
               ISDN CLASS application: caller ID, call forward, speed
                dial
   New model:
       web model: end-user and entrepreneur-created
        applications
               based on open platforms (ASP, PHP+mysql, …)
               often, hosted by content-neutral computation + network
                providers
               blogs, RSS, Wiki, podcasting, …


Feb. 2005                 Future of Telecommunications
Service creation
    Tailor a shared infrastructure to individual users
    traditionally, only vendors (and sometimes carriers)
    learn from web models

                    programmer,                end user
                    carrier
    network         SIP servlets,              CPL
    servers         sip-cgi
    end system      VoiceXML                   VoiceXML (voice),
                                               LESS


Feb. 2005           Future of Telecommunications
Program location-based services




Feb. 2005   Future of Telecommunications
             Location-based service language
     NOTIFY
       true

        false

       action            alert             IM
                                                     alert               incoming
                    proximity                        message             outgoing

conditions          occupancy    actions             log        events   notify
                                                     call
                                                                         message
                    time
                                                     transfer
                                                                         subscription
                                                     join
             Feb. 2005           Future of Telecommunications
Automating media interaction –
service examples
   If call from my boss, turn off the stereo  call
    handling with device control
   As soon as Tom is online, call him  call handling
    with presence information
   Vibrate instead of ring when I am in movie theatre 
    call handling with location information
   At 9:00AM on 09/01/2005, find the multicast session
    titled ―ABC keynote‖ and invite all the group
    members to watch  call handling with session
    information
   When incoming call is rejected, send email to the
    callee  call handling with email


Feb. 2005         Future of Telecommunications
     LESS: Decision tree
No loops
Limited variables
Not necessarily
 Turing-complete




      Feb. 2005      Future of Telecommunications
When Tom is online, …
<less>
<EVENT:notification>
 <address-switch>
   <address is="sip:tom@example.com">
    <EVENT:event-switch>
     <EVENT:event is="open">
       <location url="sip:tom@example.com">
        <IM:im message="Hi, Tom"/>
       </location>
     </EVENT:event>
    </EVENT:event-switch>
    ………
</less>




Feb. 2005         Future of Telecommunications
Feb. 2005   Future of Telecommunications
Tracking




Feb. 2005   Future of Telecommunications
Conclusion
   At inflection point from trials to
    widespread deployment
       legacy will fade except for access
   Risks to competition
       duopoly of access  tying access to
        applications
   Risks to usability


Feb. 2005         Future of Telecommunications

				
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