Endpoint vs. Network VoIP Services

1
Endpoint vs. Network VoIP Services

• Henning Schulzrinne
• (with Xiaotao Wu)
• Columbia University
• FCC Technical Advisory Council III
• Washington, DC October 20, 2003

2
What are services?

• Call routing services ? subset of CLASS services
• name/number translation
• terminal, user mobility
• call forward busy/no answer
• call forward conditional (time-of-day, call
  center)
• Directory services
• white and yellow pages
• global and corporate
• Media services
• media encoding translation for bandwidth
• media type conversion language, speech-to-text
• media combining conferencing
• Identity services
• identity assertion (Columbia attests that Joe
  Smith, an employee, is calling)
• identity hiding (agent42_at_anonymizer.com is
  calling)
• configuration repository
• media preferences
• address book and speed dial

3
PSTN vs. Internet Telephony
Internet Telephony end system
PSTN
Number of lines or pending calls is virtually
unlimited
More (per-user) processing power than most
network servers
Single line, 12 buttons and hook flash to signal
4
PSTN vs. Internet Telephony
PSTN
Signaling Media
Signaling Media
can be far away from either user
Internet Telephone
Signaling
Signaling
Media
5
PSTN vs. VoIP

• PSTN only carriers can get full signaling
  functionality (SS7)
• UNI vs. NNI signaling
• VoIP same signaling, same functionality

6
Network vs. end system services

• Really two meanings
• services implemented in user agent (instead of
  proxy)
• services implemented in server run by end user
  (instead of carrier) ?
• business
• residential
• Variation on old Centrex vs. PBX argument
• except that media routing no longer an issue
• Often, services require or can use both
• e.g., the history of speed dial
• CLASS service translation in CO
• (semi)intelligent end systems locally, possibly
  with hotsync to PC
• intelligent end system, but network-synchronized

7
End system vs. network trade-offs
8
End system vs. Network services the easier cases

• Network services
• PSTN gateway
• multiplexing gain
• SS7 access
• Backup services
• e.g., no answer from enterprise due to failure
• no permanent connectivity for residential users
• Large-scale conferences for residential users
• bandwidth availability

• End system/user services
• media processing
• distinctive ringing
• programmable services
• user control
• but security maintenance

9
Call routing services

• Outsourcing allows temporarily disconnected end
  users
• Staged service

carrier proxy
user proxy
personal preferences
basic call routing
10
Identity management

• Identity assertion (notary) services
• best done by larger organization
• server certificates
• name recognition
• recourse
• Anonymity services
• needs to have large user population to provide
  effective hiding
• Portable services
• high availability and universal reachability

11
Service architectureProgramming language model
12
Service location examples
() with information provided by end system
 
13
Analogies

• False either/or choice
• See email and web for precedent
• carrier-provided (ISPs)
• basic service
• name portability issues
• enterprise
• provide and manage own infrastructure
• only purchase raw bits
• home user
• albeit actively discouraged
• hosting companies bandwidth service
• shared and dedicated facilities
• but not an ISP in the traditional sense
• service-only companies
• web mail
• mail forwarding

14
The vanishing phone

• Old model
• explicit, user-visible signaling ? dialing,
  ringing
• small number of phone lines, (mostly) each with
  one E.164 identifier
• New model
• session initiation from
• IM session ? no dialing and ringing
• game session ? proximity triggers conversation
• event based ? connect if event occurs
• no notion of lines
• teenager (or telemarketer) may have dozens of
  chat windows open
• some identifiers may make no PSTN calls at all
• from monthly service ? calling card-like
• any number of identifiers
• one per wire or device ? multiple per person
  (role-based)

15
Example VoIP embedded in VR
16
The impact of regulations

• Phone (service) companies are not required any
  more, but may be useful
• dont have (many) email companies, either
• Regulation should not bias technical and business
  decisions on in-house vs. out-sourcing
• Avoid conflicts of interest for ISPs that provide
  phone service
• no port blocking except by user request
• traffic neutrality ? provide differentiated
  services to all
• provide externally routable addresses
• address shortage excuse ? NAT ? difficult to have
  inbound connections
• distinguish residential / business via
  application-neutral measures, e.g., bandwidth or
  availability
• Goal
• ensure transparent Internet service providers
  for added value
• encourages service innovation
• encourages service competition

17
Impact of regulations E911

• Traditional notion small number of phone
  companies (often, one) do selective routing of
  911 calls to PSAPs
• PSAP information tightly guarded
• public information, but hard/ to get
• For service competition
• should be able to route to PSAP from my home
  proxy
• open access to PSAP information
• See my ex-parte filing for details

18
Conclusions

• VoIP enables, but does not force, end point
  services
• Move service location decision to end user, with
  trade-offs in
• cost
• control
• availability
• functionality
• technical sophistication needed
• Regulatory framework should
• ensure this user choice
• prevent network operators from stifling service
  competition
• Consumer protection ? define service rules for
  effective monopoly oligopoly providers
• goal of transparent (end-to-end) Internet