1. AG Projects VON Boston - Fall 2005
Number portability
Using ENUM and SIP
Adrian Georgescu
AG Projects
http://ag-projects.com

2. AG Projects VON Boston - Fall 2005
Voice paradigm shift
The past:
• One socket in the wall
• One phone device
• One service provider
Telephone number is “wired” to the socket in the wall.
The service, device and address are hardwired to
each other by the incumbent telco.

3. AG Projects VON Boston - Fall 2005
Voice paradigm shift
Today:
• Network access - WiFi in the hotel
• SIP device - my Hitachi WIP500 phone
• PSTN service - my provider is in the Netherlands
• Identity - my address is sip:ag@ag-projects.com
Identity is the only common feature, all items are
connected together only at logical level.

4. AG Projects VON Boston - Fall 2005
What changes over time?
Each of them may change:
• I wish I have the latest and most advanced phone
• I wish I get the cheapest and fast Internet access
• I wish I call at the cheapest rates to the PSTN
• I may wish to work abroad, change location
I do not want however to change my address every
time!

5. AG Projects VON Boston - Fall 2005
Number portability today
If you can change your service provider and preserve
your telephone number, you benefit of number
portability
• Porting numbers between mobile operators
• Porting numbers between fixed line operators
• Porting numbers from mobile to fixed operators
• Porting numbers across borders (geographical)
Current telephone number portability works with limited
success and dependent on regulatory in each country

6. AG Projects VON Boston - Fall 2005
Number portability on IP
How can I be reached to my identity if I change either
the access, the device or the service?
• SIP maps Internet location of phones with SIP
addresses
• ENUM maps E.164 telephone numbers to SIP
addresses
The combination of SIP with ENUM provides an ideal
number portability solution because they combine the
logic of uniting the identity with the access, the device
and the service

7. AG Projects VON Boston - Fall 2005
SIP redirect service
• SIP as a location service supports redirection using
30X response codes (Moved temporary/permanently)
• A SIP redirect service redirects all calls unconditional
to another SIP address (final destination)
• My SIP address sip:ag@ag-projects.com is merely
an alias, it points to my sip address:
31208005169@ag-projects.com
SIP redirect works similar with email forwarding, it can
be independent of the SIP provider providing the
destination SIP address

8. AG Projects VON Boston - Fall 2005
ENUM mappings
ENUM is the “missing” link between PSTN and Internet
• ENUM is an address translation database that maps
E.164 numbers into IP addressing schemes (any)
• My ENUM number +31208005169 points to my SIP
address sip:31208005169@ag-projects.com
The ENUM mappings are records hosted in the DNS
like any other domain name. The domain hosting can
be independent of the PSTN service provider.

9. AG Projects VON Boston - Fall 2005
All together now!
The recipe for Internet number portability is:
• ENUM domain hosting
• Internet domain registration
• SIP Redirect service
• Open-garden SIP service provider
• ENUM enabled PSTN operator
• User-ENUM ready national registry (opt in)

10. AG Projects VON Boston - Fall 2005
What the user must do
?
1234@provider1.com 5678@provider2.com

11. AG Projects VON Boston - Fall 2005
What the user must do
firstName@lastName.co
m
+1-123-456789
1234@provider1.com 5678@provider2.com

12. AG Projects VON Boston - Fall 2005
What the user must do
firstName@lastName.co
m
+1-123-456789
1234@provider1.com 5678@provider2.com

13. AG Projects VON Boston - Fall 2005
On stop shop API
Send one SOAP/XML request to the Tier1 registry:
• registerAccount(domain=lastName.com,number=EN
UM)
The SOAP request is decomposed into:
– Domain registration
– DNS zone creation
– ENUM NAPTR record creation
– SIP alias creation
– Recurrent payment

14. AG Projects VON Boston - Fall 2005
Fiction or reality?
Internet number portability is already in production
status:
• ENUM.at (Austria)
• EUROVOICE.ro (Romania)

15. AG Projects VON Boston - Fall 2005

16. AG Projects VON Boston - Fall 2005
This presentation is available at
http://ag-projects.com/ENUM/
Thank you,
Adrian Georgescu
Sip/Email:ag@ag-projects.com