IMS ENUM and DNS Mechanism

1. IMS ENUM and DNS
Mechanism
IP Multimedia Subsystem Series

2. E.164 Definitions
• The international ITU-T E.164-number for geographic areas is composed of
decimal digits arranged in two code fields: the country code (CC) and the national
(significant) number N(S)N. The national (significant) number may be further
subdivided into national destination code and subscriber number fields,
according to national requirements.
CC NDC SN
1-3 digits Max (15-n) digits National Number
Max 15 digits
ITU-T E.164 number for geographic areas

3. SIP URL
P-CSCF
UE (A)
S-CSCF
AS
I-CSCF
TriggerA Party Services
DNS
Invite (SIP URL: B@domainB)
Invite (SIP URL: B@domainB)
Invite (SIP URL: B@IPAdd)
IPAdd

4. TEL URL
P-CSCF
UE (A)
S-CSCF
AS
I-CSCF
TriggerA Party Services
DNS
Invite (TEL URL: B)
Invite (TEL URL: B)
IPAdd
DNS cannot resolveTEL URL

5. ENUM Definitions
• ENUM = E.164 Number Mapping
• Telephone number mapping is a system of unifying the
international telephone number system of the public switched
telephone network with the Internet addressing and
identification name spaces.
• The E.164 number to URI DDDS (ENUM) application provides a
mapping from E.164-based "names" to various URIs, including SIP,
as defined in [RFC3761];

6. TEL URL (ENUM query success)
P-CSCF
UE (A)
S-CSCF
AS
I-CSCF
TriggerA Party Services
ENUM
Invite (TEL URL: B)
Invite (TEL URL: B)
TELURL
SIPURL
Invite (SIP URL: B@IPAdd)
IPAdd
DNS
DomainB
IPAdd

7. TEL URL (ENUM query fail)
P-CSCF
UE (A)
S-CSCF
AS
BGCF
TriggerA Party Services
ENUM
Invite (TEL URL: B)
Invite (TEL URL: B)
TELURL
Fail
Invite (TEL URL)

8. thank you