1

Barriers to EnumBarriers to EnumWhat VoIP providers ask about EnumWhat VoIP providers ask about Enum

Dr. Dorgham SisalemDr. Dorgham Sisalem

Barriers to EnumBarriers to EnumWhat VoIP providers ask about EnumWhat VoIP providers ask about Enum

Dr. Dorgham SisalemDr. Dorgham Sisalem

2

ScopeScope

– Peering: why bother– Current status of VoIP peering

– What VoIP providers ask for

– Open questions about Enum!!

3

StatusStatus

SI PSI PSI PSI P

AVM Box

SI PSI PSI PSI PSI PSI PSI PSI P

AVM Box

AVM Box

4

Why BotherWhy Bother

– VoIP works, is cheap and is nearly stable so why Bother about peering, Enum ….?

– Each VoIP service is a separate island – Suboptimal routing -> Interconnection Costs over PSTN

– Number portability– Will be a requirement when VoIP becomes first line

– Solution should support providers with „rented“ E.164 number ranges

5

Current Practices: Current Practices: PSTN InterconnectPSTN Interconnect

SI PSI PSI PSI P

AVM Box

SI PSI PSI PSI PSI PSI PSI PSI P

AVM Box

AVM Box

– Connect over PSTN– Inefficient routing

– Higher costs

– Possible lower QoS

– Services restricted to common denominator

– LNP – Use current LNP database

– No support for rented numbers

– Need to couple IP devices with legacy infrastructure

6

Current Practices: Current Practices: Direct InterconnectDirect Interconnect

SI PSI PSI PSI P

AVM Box

SI PSI PSI PSI PSI PSI PSI PSI P

AVM Box

AVM Box

– Inter-provider agreements– All numbers with prefix X are

routed to provider Y

– Exchange E.164 number ranges

– Administration overhead is a nightmare

– LNP nearly impossible

– High level of trust and cooperation between

competing providers

7

Current Practices: Current Practices: Private Number ExchangePrivate Number Exchange

SI PSI PSI PSI P

AVM Box

SI PSI PSI PSI PSI PSI PSI PSI P

AVM Box

AVM Box

– Efforts lead by certain providers to allow exchange of numbers

– No wide acceptance

– No clear funding and support structure

– No clear technical evaluation – Scalability

– Privacy and security

NEX

8

What are VoIP providers What are VoIP providers looking forlooking for

– An entity that provides the technological infrastructure for supporting – Number routing

– LNP

– This entity must be– A service provider for VoIP providers

– Politically independent

– Technologically capable

• Based on LNP/MNP Experience– Central Database for consistency

– Distributed caches for performance

– Open interfaces– Announce number ranges

– Announce ported numbers

– Specify provider specific rules

9

Proposed SolutionProposed SolutionProposed SolutionProposed Solution

SI PSI PSI PSI P

AVM Box

SI PSI PSI PSI PSI PSI PSI PSI P

AVM Box

AVM Box

Central DB

10

ENUMENUM

SI PSI PSI PSI P

AVM Box

SI PSI PSI PSI PSI PSI PSI PSI P

AVM Box

AVM Box

– The magic cure for everything?

– Technology is rather understood but still many open questions

ENUM

11

ENUM: VoIP providersENUM: VoIP providers

– Control: Who is running the infrastructure? – Do the providers have a say on

– how the system should look like?

– How much things should cost?

– What the interfaces should look like?

– Providers in Germany are looking at industry organizations for playing this rule

– Privacy: Who sets the policy?– Can the providers set their own privacy and number

transparency policies?– Show my numbers to provider A but not to provider B?

12

ENUM: TechnologyENUM: Technology

– Scalability: ENUM is NOT as scalable as DNS– Caching is useless

– Would be similar to have a mail server to cache email addresses

– Transport: NAPTR records can very easily exceed the UDP size

– Fragmentation problems

– Bandwidth load on the central ENUM server

– Performance– Measurements suggest query times between 500 msec and

2500 msec

– LNP and Delegation: With delegation only complete number ranges are delegated to another server

– With LNP some central server will need to maintain all the numbers

13

ENUM: PrivacyENUM: Privacy

– Some privacy advocates claim:– Anonymity is no longer supported

– To be reached one has to publish the phone number

– Too much information about the users in a central location

– Could be misused by governments

14

ENUM: ConclusionENUM: Conclusion

– To successfully sell the technology one should concentrate less on technology and provisioning interfaces and more on– Address concerns of VoIP providers and privacy advocates

– Conduct large scale performance tests taking into account:– Scalability

– Answer times with complex NAPTR records

– LNP

– The results of such tests and answers should be easily accessible