Endpoint vs. Network VoIP Services Henning Schulzrinne (with Xiaotao Wu) Columbia University FCC Technical Advisory Council III Washington, DC – October 20, 2003

What are services? Call routing services  subset of CLASS services name/number translation terminal, user mobility call forward busy/no answer call forward conditional (time-of-day, call center) Directory services white and yellow pages global and corporate Media services media encoding translation for bandwidth media type conversion: language, speech-to-text media combining: conferencing Identity services identity assertion (“Columbia attests that Joe Smith, an employee, is calling”) identity hiding (“agent42@anonymizer.com is calling”) configuration repository media preferences address book and speed dial

PSTN vs. Internet Telephony end system PSTN Number of lines or pending calls is virtually unlimited Generally, end system in Internet Telephony logically have multiple lines. It can deal with unlimited incoming phone calls. PCs can be considered as the end-user devices and can perform many service functionalities. Unlimited lines, no feature interaction, good or not? Keep all the things in human’s mind? More (per-user) processing power than most network servers Single line, 12 buttons and hook flash to signal

PSTN vs. Internet Telephony Signaling & Media Signaling & Media can be far away from either user With a few exceptions, in Internet telephony, end systems are the only entities where signaling and media flows converge. Thus, any service that requires interaction with user media is likely to be easier to implement in the end systems. More seperately Internet Telephone: Signaling Signaling Media

PSTN vs. VoIP PSTN: only carriers can get full signaling functionality (SS7) UNI vs. NNI signaling VoIP: same signaling, same functionality

Network vs. end system services Really two meanings: services implemented in user agent (instead of proxy) services implemented in server run by end user (instead of carrier)  business residential Variation on old Centrex vs. PBX argument except that media routing no longer an issue Often, services require or can use both: e.g., the history of speed dial CLASS service: translation in CO (semi)intelligent end systems: locally, possibly with hotsync to PC intelligent end system, but network-synchronized

End system vs. network trade-offs Criteria network end system availability high (backup systems & power) lower, but maintain local services during network outage bandwidth high lower ( large centralized conferences) addressing global IPv4 addresses often NATs  can’t run servers IPv6 may fix security professional maintenance more visible target trust third party with content update tracking lower disruption end-to-end encryption user control protection of shared resources  limit user programmability full control processing high aggregate, lower per-user low on residential GW, unbounded on PCs

End system vs. Network services – the easier cases PSTN gateway multiplexing gain SS7 access Backup services e.g., no answer from enterprise due to failure no permanent connectivity for residential users Large-scale conferences for residential users bandwidth availability End system/user services media processing distinctive ringing programmable services user control but: security maintenance

Call routing services Outsourcing allows temporarily disconnected end users Staged service: carrier proxy user proxy personal preferences basic call routing

Identity management Identity assertion (notary) services best done by larger organization server certificates name recognition recourse Anonymity services needs to have large user population to provide effective hiding Portable services high availability and universal reachability

Service architecture Programming language model

Service location examples End system Network (proxy) Network with media (UA) Distinctive ringing Yes Can assist Visual call id Call waiting No Yes(*) CF busy CF no answer CF no device Location hiding Transfer Conference bridge Gateway to PSTN Firewall control Voicemail (*) = with information provided by end system  

Analogies False either/or choice See email and web for precedent carrier-provided (ISPs) basic service name portability issues enterprise provide and manage own infrastructure only purchase “raw bits” home user albeit actively discouraged hosting companies = bandwidth + service shared and dedicated facilities but not an ISP in the traditional sense service-only companies web mail mail forwarding

The vanishing phone Old model: New model: explicit, user-visible signaling  dialing, ringing small number of phone lines, (mostly) each with one E.164 identifier New model: session initiation from IM session  no dialing and ringing game session  proximity triggers conversation event based  connect if event occurs no notion of lines teenager (or telemarketer…) may have dozens of chat windows open some identifiers may make no PSTN calls at all from monthly service  calling card-like any number of identifiers one per wire or device  multiple per person (role-based)

Example: VoIP embedded in VR

The impact of regulations Phone (service) companies are not required any more, but may be useful don’t have (many) email companies, either Regulation should not bias technical and business decisions on in-house vs. out-sourcing Avoid conflicts of interest for ISPs that provide phone service: no port blocking except by user request traffic neutrality  provide differentiated services to all provide externally routable addresses address shortage excuse  NAT  difficult to have inbound connections distinguish residential / business via application-neutral measures, e.g., bandwidth or availability Goal: ensure “transparent Internet” + service providers for added value encourages service innovation encourages service competition

Impact of regulations: E911 Traditional notion: small number of phone companies (often, one) do selective routing of 911 calls to PSAPs PSAP information tightly guarded public information, but hard/$$$ to get For service competition: should be able to route to PSAP from my home proxy open access to PSAP information See my ex-parte filing for details

Conclusions VoIP enables, but does not force, end point services Move service location decision to end user, with trade-offs in cost control availability functionality technical sophistication needed Regulatory framework should ensure this user choice prevent network operators from stifling service competition Consumer protection  define service rules for effective monopoly & oligopoly providers goal of transparent (end-to-end) Internet