1. Interactive Communications – voice, video, IM and presence-based services
Henning Schulzrinne
(with Jonathan Lennox, Mathew Mintz-Habib, Anshuman Rawat, Ron Shacham, Xiaotao Wu)
Columbia University
Lucent Bell Labs
November 15, 2004
Nov. 2004
VoIP

2. Overview The state of VoIP Context & location-based services
Service creation in end systems
Service and session mobility
Emergency calling
Spam, spit and other unsavory things
What is identity?
What’s left to do?
VoIP
Nov. 2004

3. (Early) Adulthood “fully developed and mature” Responsibilities:
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
VoIP
Nov. 2004

4. long-distance calling,
Evolution of VoIP
“how can I make it
stop ringing?”
long-distance calling,
ca. 1930
“does it do
call transfer?”
going beyond
the black phone
“amazing – the
phone rings”
catching up
with the digital PBX
2004-
VoIP
Nov. 2004

5. The state of SIP
VoIP
Nov. 2004

6. SIP is PBX/Centrex ready
boss/admin features
call waiting/multiple calls
RFC 3261
hold
RFC 3264
transfer
RFC 3515/Replaces
conference
RFC 3261/callee caps
message waiting
message summary package
call forward
call park
call pickup
Replaces
do not disturb
call coverage
simultaneous ringing
RFC 3261
basic shared lines
dialog/reg. package
barge-in
Join
“Take”
Replaces
Shared-line “privacy”
dialog package
divert to admin
intercom
URI convention
auto attendant
RFC 3261/2833
attendant console
night service
centrex-style features
attendant features
VoIP
from Rohan Mahy’s VON Fall 2003 talk
Nov. 2004

7. A constellation of SIP RFCs
Non-adjacent (3327)
Symmetric resp. (3581)
Service route (3608)
User agent caps (3840)
Caller prefs (3841)
Request routing
Resource mgt. (3312)
Reliable prov. (3262)
INFO (2976)
UPDATE (3311)
Reason (3326)
SIP (3261)
DNS for SIP (3263)
Events (3265)
REFER (3515)
ISUP (3204)
sipfrag (3240)
Mostly PSTN
Content types
Core
Digest AKA (3310)
Privacy (3323)
P-Asserted (3325)
Agreement (3329)
Media auth. (3313)
AES (3853)
DHCP (3361)
DHCPv6 (3319)
Configuration
VoIP
Nov. 2004
Security & privacy

8. SIP, SIPPING & SIMPLE –00 drafts
includes draft-ietf-*-00 and draft-personal-*-00
VoIP
Nov. 2004

9. Protocol interoperability problems
Three core interoperability problems:
syntactic robustness
“You mean you could have a space there?”
often occurs when testing only against common reference implementations
need “stress test” (also for buffer overflows)
implementation by protocol example
limiting assumptions (e.g., user name format)
see “SIP Robustness Testing for Large-Scale Use”, First International Workshop on Software Quality (SOQA)
semantic assumptions
“I didn’t expect this error”
mutually incompatible extensions
expect extension to make something work
VoIP
Nov. 2004

10. Protocol interoperability
Proprietary protocol
Example: Skype
Can only reverse-engineer  only backwards-compatibility problems
incentive to force upgrades (see Microsoft Word)
quicker evolution, but limited product selection
less Metcalfe’s law value
Open standard, but dominant vendor
Example: H.323, Asterix
doesn’t matter what the standard says
NetMeeting and H.323  test with Microsoft implementation
limits feature evolution to dominant vendor speed
Open standard, multiple large and many small vendors
Example: SIP
hardware vs. software, UA vs. proxy, phones vs. gateways
interoperability problems until product maturity
harder to test internally against all (competing) products
better long-term outcome, but slower
VoIP
Nov. 2004

11. Context-aware and location-based services
VoIP
Nov. 2004

12. Context
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)
not yet, but similar in many aspects to location data
VoIP
Nov. 2004

13. “Legacy” IM & presence systems  SIP-based systems
centralized systems (single name space)
federated systems, similar to
mostly instant text messages
media-agnostic – transmit any media object
separate from session-based services (VoIP, video conferencing)
integrated:
use IM as part of media sessions
use presence to facilitate session setup
limited presence status, mostly manually set
rich presence, with time information
imported from sensors, calendars, backend systems, …
proprietary systems (AOL, Yahoo!, MSN, ICQ, …)
standards-based systems
VoIP
Nov. 2004

14. Presence and event notification
Presence = special case of event notification
“user Alice is available for communication”
Human users:
multiple contacts per presentity
device (cell, PDA, phone, …)
service (“audio”)
activities, current and planned
surroundings (noise, privacy, vehicle, …)
contact information
composing (typing, recording audio/video IM, …)
Multimedia systems:
REFER (call transfer)
message waiting indication
conference floor control
conference membership
push-to-talk
system configuration
General events:
emergency alert (“reverse 911”)
industrial sensors (“boiler pressure too high”)
business events (“more than 20 people waiting for service”)
VoIP
Nov. 2004

15. 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 presence
configuration (XCAP)
session-oriented IM (↔ page mode)
filtering, rate limiting and authorization
VoIP
Nov. 2004

16. Presence data model “calendar” “cell” “manual” person (views) services
audio, video, text
video
services
devices
VoIP
Nov. 2004

17. GEOPRIV and SIMPLE architectures
rule
maker
DHCP
XCAP
(rules)
target
location
server
location
recipient
publication
interface
notification
interface
GEOPRIV
SUBSCRIBE
presentity
presence
agent
watcher
SIP
presence
PUBLISH
NOTIFY
caller
callee
SIP
call
INVITE
INVITE
VoIP
Nov. 2004

18. RPID: rich presence
Provide watchers with better information about the what, where, how of presentities
facilitate appropriate communications:
“wait until end of meeting”
“use text messaging instead of phone call”
“make quick call before flight takes off”
designed to be derivable from calendar information
or provided by sensors in the environment
allow filtering by “sphere” – the parts of our life
don’t show recreation details to colleagues
VoIP
Nov. 2004

19. RPID: rich presence Classification: User activities: service class
device, in-person, service, presentity
class
for labeling
sphere
“work”, “home”, …
relationship
“family”, “associate”, “assistant”, “supervisor”
User activities:
activities
“on-the-phone”, “away”, “appointment”, …
user-input
last usage of device
Mood
Surroundings:
time offset
place-type
“home”, “office”, “industrial”, …
privacy
“public”, “private”
VoIP
Nov. 2004

20. CIPID: Contact Information
More long-term identification of contacts
Elements:
card – contact Information
home page
icon – to represent user
map – pointer to map for user
sound – presentity is available
VoIP
Nov. 2004

21. Timed Status Presence is about here & 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
loose synchronization of calendars
<tuple id="7c8dqui">
<contact>
</contact>
<status>
<basic>open</basic>
</status>
<fs:timed-status
from=" T10:20: :00“
until=" T19:30: :00">
<basic>closed</basic>
</fs:timed-status>
</tuple>
<note>I'll be in Tokyo next week</note>
VoIP
Nov. 2004

22. Location-based services
Finding services based on location
physical services (stores, restaurants, ATMs, …)
electronic services (media I/O, printer, display, …)
not covered here
Using location to improve (network) services
communication
incoming communications changes based on where I am
proximity triggers communications
configuration
devices in room adapt to their current users
awareness
others are (selectively) made aware of my location
security
proximity grants temporary access to local resources
VoIP
Nov. 2004

23. Location-based SIP services
Location-aware inbound routing
do not forward call if time at callee location is [11 pm, 8 am]
only forward time-for-lunch if destination is on campus
do not ring phone if I’m in a theater
outbound call routing
contact nearest emergency call center
send to nearest branch
location-based events
subscribe to locations, not people
Alice has entered the meeting room
subscriber may be device in room  our lab stereo changes CDs for each person that enters the room
VoIP
Nov. 2004

24. Location detection
VoIP
Nov. 2004

25. DHCP for locations
modified dhcpd (ISC) to generate location information
use MAC address backtracing to get location information
8:0:20:ab:d5:d
DHCP
server
CDP + SNMP
8:0:20:ab:d5:d  458/17
DHCP answer:
sta=DC loc=Rm815
lat= long=
458/17  Rm. 815
458/18  Rm. 816
VoIP
Nov. 2004

26. SIP URIs for locations
location beacon
Identify confined locations by a SIP URI, e.g.,
Register all users or devices in room
Allows geographic anycast: reach any party in the room
sip:rm815
Contact: bob
Contact: alice
Room 815
VoIP
Nov. 2004

27. Describe a location Geospatial coordinates Civic address
e.g., measured by GPS
expressed in PIDF-LO as GML:
<gml:coordinates>40:48:34N 73:57:39W</gml:coordinates>
Civic address
National Emergency Number Association (NENA)
<location country="USA" A1="NY" A3="New York" A6="West 120th Street" HNO="500" LOC="450">
Location attributes
place type, noise, media privacy, number of people, moving, …
VoIP
Nov. 2004

28. Privacy All presence data, particularly location, is highly sensitive
Basic location object (PIDF-LO) describes
distribution (binary)
retention duration
Policy rules for more detailed access control
who can subscribe to my presence
who can see what when
<tuple id="sg89ae">
<status>
<gp:geopriv>
<gp:location-info>
<gml:location>
<gml:Point gml:id="point1“
srsName="epsg:4326">
<gml:coordinates>37:46:30N 122:25:10W
</gml:coordinates>
</gml:Point>
</gml:location>
</gp:location-info>
<gp:usage-rules>
<gp:retransmission-allowed>no
</gp:retransmission-allowed>
<gp:retention-expiry> T04:57:29Z
</gp:retention-expiry>
</gp:usage-rules>
</gp:geopriv>
</status>
<timestamp> T20:57:29Z</timestamp>
</tuple>
VoIP
Nov. 2004

29. Privacy policy relationships
common policy
geopriv-specific
presence-specific
future
RPID
CIPID
VoIP
Nov. 2004

30. Privacy rules
Conditions
identity, sphere, validity
time of day
current location
identity as <uri> or <domain> + <except>
Actions
watcher confirmation
Transformations
include information
reduced accuracy
User gets maximum of permissions across all matching rules
Extendable to new presence data
rich presence
biological sensors
mood sensors
VoIP
Nov. 2004

31. Location-based service language
NOTIFY
true
false
action
alert IM
alert
incoming
proximity
message
outgoing
log
conditions
occupancy
actions
events
notify
call
message
time
transfer
subscription
join
VoIP
Nov. 2004

32. Program location-based services
VoIP
Nov. 2004

33. VoIP
Nov. 2004

34. Tracking
VoIP
Nov. 2004

35. Overview of SIPc functions
emergency
configuration
handling
multimedia
session setup
presence
network
multicasted session
information
appliance control
clients
Web browsers
Instant
message
Network appliance control
Third party call control
Real time streaming
audio
video
Emergency handling
SIP
Multimedia
call control
SIP CGI
engine
white
board
SAP
location
sensors
Location sensing
SIP for presence
Floor
control
LESS/CPL
engine
Service Location
Detection (SLP)
desktop
sharing
Some IETF drafts
CPL, SIP 3PCC,
SIP Device Control
GEOPRIV location format, SIP for IM
SIP: RFC 3261
SAP: RFC 2974
RTSP: RFC 2326
SDP: RFC 2327
RTP: RFC 1889
SLP: RFC 2608
VoIP
Nov. 2004
SIP Event Notification: RFC 3265

36. Evolving Conferencing floor control Device control Presence
notification
ir/x10
xcon
Location
tracking
SIP event
notification
Service
detection
Message
waiting
indication
Location
sensing
SIP
SLP
Voic
handling
Call
Emergency
handling
RTP
SDP
MapLynx
RTSP
Instant
messaging
Session
broadcasting
SAP
VoIP
Nov. 2004

37. Internet2 WG PIC trial SUBSCRIBE to my location NOTIFY myself PUBLISH
and others’
locations
PUBLISH
presence
status
VoIP
Nov. 2004

38. Ubiquitous computing SA DA SA turn on projector Service Location Query
send
audio
Resource
Network
to SIP
Discovery
Appliance
UA2
(SLP UA)
Control
audio
and
Script
Resource
video
engine
Control
streams
(3pcc)
SIP UA1
SIP
VoIP
Nov. 2004
call
UA2

39. Service scenario Media streams Front desk SIP Server SLP Server Hotel
Room 123
Bluetooth
Use
Authenticate
Call
Location
Visitor
Resources
Call
Info
Resource
Info
Home domain
Register
SIP and AAA
server
VoIP
Nov. 2004

40. Example: user-adaptive device configuration
“all devices that are in the building”
RFC 3082?
signal strength  location
SLP
device
controller
HTTP PA
REGISTER
To: 815cepsr
Contact:
tftp
SUBSCRIBE
to each room
discover room URI
REGISTER as contact for room URI
SIP
room 815
SUBSCRIBE to configuration
for users currently in rooms
VoIP
Nov. 2004

41. Service creation
VoIP
Nov. 2004

42. Service creation Tailor a shared infrastructure to individual users
traditionally, only vendors (and sometimes carriers)
learn from web models
programmer, carrier
end user
network servers
SIP servlets, sip-cgi
CPL
end system
VoiceXML
VoiceXML (voice),
LESS
VoIP
Nov. 2004

43. 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 to the callee  call handling with
VoIP
Nov. 2004

44. LESS: simplicity Generality (few and simple concepts)
Uniformity (few and simple rules)
Trigger rule
Switch rule
Action rule
Modifier rule
Familiarity (easy for user to understand)
Analyzability (simple to analyze)
modifiers
trigger
switches
actions
VoIP
Nov. 2004

45. LESS: Decision tree No loops Limited variables Not necessarily
Turing-complete
VoIP
Nov. 2004

46. LESS: Safety Type safety Control flow safety Memory access
Strong typing in XML schema
Static type checking
Control flow safety
No loop and recursion
One trigger appear only once, no feature interaction for a defined script
Memory access
No direct memory access
LESS engine safety
Ensure safe resource usage
Easy safety checking
Any valid LESS scripts can be converted into graphical representation of decision trees.
VoIP
Nov. 2004

47. Accept the call with only audio
LESS snapshot
incoming call
<less>
<incoming>
<address-switch>
<address
<device:turnoff
<media media=“audio”>
<accept/>
</media>
</address>
</address-switch>
</incoming>
</less>
If the call from my boss
Turn off the stereo
Accept the call with only audio
trigger, switch, modifier, action
VoIP
Nov. 2004

48. LESS packages Use packages to group elements SIP user agent SIP im
web
Device agent
x10
vcr
Presence
agent
presence
Event
Basic user agent
Generic
Media UI
calendar
conference
session
location
VoIP
Nov. 2004

49. When Tom is online, … <less> <EVENT:notification>
<address-switch>
<address
<EVENT:event-switch>
<EVENT:event is="open">
<location
<IM:im message="Hi, Tom"/>
</location>
</EVENT:event>
</EVENT:event-switch>
………
</less>
VoIP
Nov. 2004

50. When I am in a movie theatre, …
<less>
<incoming>
<location-switch>
<location placetype=“quiet”>
<alert sound=“none” vibrate=“yes”/>
</location>
</location-switch>
</incoming>
</less>
VoIP
Nov. 2004

51. Emergency Services
VoIP
Nov. 2004

52. 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
Phase II wireless (30%)
call delivery based on geo address
geo location delivery to PSAP
VoIP
Nov. 2004

53. 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
VoIP
Nov. 2004

54. How does VoIP differ from landline and wireless PSTN?
Telephone companies are no longer needed
there are still carriers for DSL and cable “IP dial tone”
but unaware of type of data carried
VSP may be in another state or country
Corporations and universities don’t have carriers, either
voice service provider
(RTP, SIP)
Yahoo
ISP
(IP, DHCP, DNS)
MCI
dark fiber
provider
NYSERNET
VoIP
Nov. 2004

55. Three stages to VoIP 911 I1 I2 I3 spec. available?
use 10-digit admin. number?
mobility
callback
number to PSAP?
caller
location to PSAP?
PSAP
modification
ALI (DB)
new services I1
now
allowed
stationary no
none I2
Dec. 2004
nomadic
yes
no (8 or 10 digit)
update I3
2005
mobile
IP-enabled
ALI not needed
MSAG replaced by lookup proto (DNS, IRIS?)
location in-band
GNP
multimedia
international calls
VoIP
Nov. 2004

56. I3: Location-based call routing – UA knows its location
GPS
INVITE
48° 49' N 2° 29' E
outbound
proxy server
DHCP
48° 49' N 2° 29' E  Paris fire department
VoIP
Nov. 2004

57. I2 architecture (draft)
DBMS
IP domain
Emergency Services
Provider Network
Call server/
proxy server
PSTN
Routing Proxy &
Redirect
server(s )
MSAG E9 - 1
Selective
Router
VDB v6
ALI DB
ESGW(s ) v5 v4 v4 E9 - 1 - 1
ESZ
RDB
DHCP
Selective
PSAP
DNS v1
Router
LIS
IP Domain v2
User v2
VPC
Agent
VPC
SRDB
VPC v - e2 v0
ALI DB v8 v3 v7
location information
service
VoIP positioning center
routing database
validation database
VoIP
Nov. 2004

58. I2 example (embedded LO)
VoIP
Nov. 2004

59. Components sipd sipc SIP proxy server database-backed DNS server
SIP phone
web server
SQL database for call routing
sipc
SIP user agent
geo-coding, PSAP boundaries
GIS software for call location plotting
No endorsement implied – other components likely will work as well
VoIP
Nov. 2004

60. I3 prototype
* gray features in progress.
VoIP
Nov. 2004

61. Detail: I3 - DNS-based resolution
DHCP INFORM
psap.state.vt.gov
SIP w/location
MAC  loc
Perl sip-cgi script
psap.state.vt.gov
DNS NAPTR:
addison.vt.us
algonquin-dr.addison.vt.us …
proprietary
TCP-based
protocol
151.algonquin-dr.addison.vt.us.sos-arpa.net
VoIP
Nov. 2004

62. GeoLynx displays location
GeoLynx listens for commands from SIPc
VoIP
Nov. 2004

63. Spam and spit
VoIP
Nov. 2004

64. SIP unsolicited calls and messages
Possibly at least as large a problem
more annoying (ring, pop-up)
Bayesian content filtering unlikely to work
 identity-based filtering
PKI for every user unrealistic
Use two-stage authentication
SIP identity work
mutual
PK authentication (TLS)
home.com
Digest
VoIP
Nov. 2004

65. 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
VoIP
Nov. 2004

66. Reputation service Bob Alice is this a spammer? David Carol Frank
has sent
IM to
has sent to
Frank
Emily
is this a spammer?
Bob
Alice
VoIP
Nov. 2004

67. What else is left? A random selection
Higher-level service creation in end systems
The role of intermediaries
session-border controllers
end-to-middle security
session policies
Conferencing
IETF XCON WG struggling with model and complexity
Application sharing (~ remote access)
pixel-based
semantically-based
VoIP
Nov. 2004

68. Conclusion
VoIP is
VoIP
Nov. 2004