TIPHON Perspective on
VoIP Numbering
John Horrocks (DTI)
Tiphon WG4 Chair
Document IPW-11
1
Tiphon
• Numbering relates to services not technology
• Regulation depends on services not technology
• IP can support many different services
• Aiming primarily at needs of telcos who migrate services onto IP
• Naming based on E.164 for public telephony (alternatives not
excluded)
• Expect telcos will want protected boundaries so design for
step/step call set-up with migration to end-end (hacking, quality
control, call related charging, culture)
• Not dependent on public E.164-IP resolution system for starting
2
Names and Addresses: Basics-1
• Name: Unique identifier of
communicating entity, used by network,
may be structured for user and contain
geographic information
• Address: Location of entity in terms of
network structure
3
Names and Addresses: Basics-2
Telephony
Email
Telephony
on IP
Tiphon
“IP
Telephony”
IETF
Name
E.164
User@host
E.164
User@host
Address
Routing
E.164 or
Prefix+E.164
IP address
IP address
IP address
Acknowledgement: DGTP Netherlands
4
Main current work areas
• IETF: IPTEL general work based on SIP
• ENUM selection of means to
communicate with E.164 number, based
on DNS, precursor to use of SIP for call
• IETF: PINT Control connection between
PSTN dial-up access and ISP
• Tiphon: E.164 to IP resolution
Acknowledgement: DGTP Netherlands
5
Where Tiphon fits in
(Search engines)
Tiphon
E.164
ENUM
Services
E.164
E.164
Choice
Services
E.164
URL
E.164
SIP
IPTEL
User@host
Acknowledgement: DGTP Netherlands
IP address
6
Different service concepts
Common service model
Different service model
ETSI Tiphon
H.323
Voice telephony service
E.164
Switched
circuit
networks
IP
networks
IETF
SIP
SCN telephony
E.164
IP telephony
User@host
+ E.164
Switched
circuit
networks
IP
networks
Acknowledgement: DGTP Netherlands
7
Common service numbering
ITU-T
NRA-1
Operator-1a
Operator-1b
Operator-1c
Operator-1d
NRA-2
NRA-3
ICANN
NRA-4
Operator-2a
Operator-2b
Operator-2c
Operator-2d
SCN operators and IP operators
All registration activity is here
Only operators know and can authorise individual
number assignments unless there is a full national
database
Authorisation
and data
needed from IP
operators
E.164 server system
modelled on DNS
Contains E.164-IP address pairs for each
E.164 number served on an IP network.
IP addresses point to destination networks
and not necessarily to the terminals
Needed for E.164 - IP resolution
Customers of IP operators allocated
E.164 numbers under this system
Acknowledgement: DGTP Netherlands
No updating from users or
IP based operators without
allocation from NRA
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The Future: Multi-Everything
Multiple Users
(different roles, different persons,
distinctive alerting)
Multiple terminals
Multiple accesses
(eg fixed, mobile 1, mobile 2)
Multiple service providers
Multiple services
(eg telephony, fax data, video)
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Future caller needs
Easy
Dial
Class A
“closed user groups”
Easy
“Mem”
Easy
Find
Customisation
Class B
“public numbers”
Registered names
Class C
“random calls”
Directories
10
Future solutions
• Avoid a wholly new system allow
smooth market-led migration
• Grow E.164 for different roles/labels
• Hide E.164 with better terminals and
search engines
• Work needed on privacy vs exchange of
information to facilitate search engines
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Tiphon Approach
• Many different voice related services
supported on IP
• E.164 use depends on service
implemented
• Interconnected networks with real
boundaries
• Allow Step-by-step call set-up
12
Service
resolution
(may be repeated)
Service information
could also be accessed
by later gatekeepers
Service
information
E.164 - IP routing
resolution
(may
be repeated)
Service information
Search
resolution
E.164 - IP local endpoint
resolution
(may be repeated)
may be accessed
either from SCN or IP
E.164-IP
Resolver
Address book
Search engine
or Directory
Any information
on called party
E.164 - IP routing
resolution
(may be repeated)
Called or
Routing
E.164
E.164 number
(directory number)
E.164-IP
Resolver
Next hop
information
Called or
Routing
E.164
Gatekeeper
Called
E.164
Routing
E.164
E.164-IP
Resolver
Next hop
information
Called or
Routing
E.164
Home
Gatekeeper
Gatekeeper
IP address
for media
If present
Terminal
information
IP address
for media
H.225 signalling
Media
Calling
terminal
Route on
called E.164
SCN
switch
Ingress IP
gateway
There are various
options for this signalling
Route on
routing E.164
Routing mostly uses tables
in SCN switches. One switch
may use IN for service information
SCN technology
IP technology
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Resolves R(E.164)
into IP address for
Gatekeeper at
destination
Service
resolution
Service
information
Home
Gatekeeper
Service control
Service control
Routes on IP address
but carries calling & called E.164
R(E.164)
Cd(E.164)
Ingress
Gatekeeper
Call control
R(E.164)
R(E.164)
R(E.164)
Cd(E.164)
Checks availability
of terminal
Negotiates IP addresses
for media channel
Call control
IP address of terminal
media port
SCN
switch
SCN
switch
Possible
network
boundary
Possible
network
boundary
Possible
network
boundary
Signalling
Signalling I’face
IP Routing (UDP)
Media I’face
Ingress
Gateway
Possible
extension
to SCN
H.225 signalling
Opens media
SCN
switch
Call control
Uses IP address from call control
contains implicit call identification
Media
Terminal (or
gateway
back to SCN)
Possible
network
boundary
Uses available interconnections
may give some quality control
SCN
Signalling
Media
IP
Cd(E.164) = Called E.164 number
R(E.164) = Routing E.164 number
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E.164 - IP Routing
Resolution
E.164 - IP Local Endpoint
Resolution
SC
1a - Cd R(E.164)
or Cd (E.164)
4a - Cd R(E.164)
2a - S2i
When 2a +2b
received
Start
SC
3 - Set-up
6 - Set-up
contains S1o
may contain M1o
contains S2o
may contain M2o
S2i
CC
Signalling
12 - Connect
may contain M2i
2b - M1o
reserved
13 - Activate media
S2o
BC
11 - Connect pairs
(M2i,MTi), (M2o, M1o)
2b - M1o
reserved
13 - Activate media
BC
M2i
4b - Reserve
media
11 - Connect pairs
(M2i,MTi), (M2o, M1o)
5b - M2i, M2o
reserved
MC
7 - Reserve
media
9 - Activate
media
8 - MTi
Reserved
MTi
MC
M1o
Ingress
Gateway
8 - MTi
Reserved
BC
MTi
M2i
Bearer
CC
10 - Connect
may contain MTi
7 - Reserve
media
5b - M2i, M20
9 - Activate
reserved
media
M2o
4b - Reserve
media
M1o
1b - Reserve
media
STi
CC
S1o
1b - Reserve
media
5a - STi
MC
M2o
Call set-up direction
Home
Gateway
Terminal
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SC
SC
4a - Cd R(E.164)
2a - S2i
1a - Cd R(E.164)
When 2a +2b
received
Start
3 - Set-up
contains S1o
may contain M1o
6 - Set-up
S2i
contains S2o, M2o
CC
CC
S1o
1b - Reserve
media
9 - Connect
may contain M2i
2b - M1i, M1o
reserved
10 - Connect pairs
(M1i,M2i), (M1o, M0o)
5a - S3i
S2o
4b - Reserve
media
7 - Connect
5b - M2i, M20
reserved
8 - Connect pairs
(M2i,M3i), (M2o, M1o)
M1o
BC
1b - Reserve
media
10 - Connect pairs
(M1i,M2i), (M1o, M0o)
BC
M2i
2b - M1i, M1o
reserved
4b - Reserve
media
5b - M2i, M2o
reserved
8 - Connect pairs
(M2i,M3i), (M2o, M1o)
M1i
M2i
MC
Network 1
Gateway
MC
M1o
Call set-up direction
Network 2
Gateway
M2o
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