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Subject: SIP in higher education

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Notes from VoIP call - February 8, 2007

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  • From: Garret Yoshimi <>
  • To: Internet2 VoIP SIG <>, "Internet2" <>
  • Subject: Notes from VoIP call - February 8, 2007
  • Date: Thu, 22 Feb 2007 14:29:56 -1000
  • Organization: University of Hawaii

Notes from VoIP Conference Call February 8th, 2007
(Thanks once again to Jeff Kuure for compiling these notes!)


Steve Blair, University of Pennsylvania
Chris Casswell, MCNC
Candace Holman, Harvard Deke Kassabian, University of Pennsylvania
Sean Kent, Level 3
Walt Magnussen, Texas A&M
Joe Milander, University of Oregon
Chris Norton, Texas A&M
Carey Tengler, Level 3
Jonathon Tyman, Internet2
Mike Van Norman, UCLA
Garret Yoshimi, University of Hawaii


Today's call features Steve Blair and Deke Kassabian from the University of
Pennsylvania discussing their recent work with Level 3 communications.

Sean Kent, part of a Product Technical Specialist team for Level 3, is on the call to provide an overview of Level 3's services. Carey Tengler, manager of Level 3's Technology Partner Program, is also present. Sean says that Level 3's products are currently targeted at wholesale voice communication companies, but they are looking to work with educational and research organizations as well. In terms of products, they offer voice termination for long distance, local inbound service for DID termination to SIP endpoints, toll free service for PSTN traffic to SIP endpoints, and their enhanced local services, which is a combination of LI and VT products bundled with information services, directory listings, 911, and operator services.
For getting onto the Level 3 network, they provide a Web interface for
interoperability testing which gathers end user information through a
certified soft switch. Level 3 is not a SIP registrar, so rather than
registering SIP endpoints they would communicate with IP devices such as a
SER or Broadsoft server. The Web application enables end users to perform
interoperability testing at their own pace. There are sets of tests for both
inbound and outbound traffic, with reports generated for approximately 20
possible call flow scenarios. Some customers have completed the tests over a
couple of days, with others taking several months. Typically the tests are
completed in four to six weeks. Sean estimates that for a new client it would
take one to two months to run the tests, sign any contracts, and begin
passing live traffic with Level 3.

Following this, Carey talks about Level 3's Technology Alliance Program which
deals with interoperability issues with different vendors. The bulk of the
vendors mentioned on Level 3's website are focused on hosting, but a number
are migrating to a SIP trunking scenario. Broadsoft is one participant, as
are other PBX vendors like Linksys, Cisco, Avaya, 3COM, Nortel, and Digium.
Level 3 is still working out the formalities of the interoperability process
as well as trying to become more proactive in anticipating customer's
demands. The TAP program does support all of the business divisions within
Level 3, and covers everything from OSS and BSS applications for back office
and provisioning to enterprise solutions for voice and data.

Deke and Steve begin to discuss their experience with Level 3 at the
University of Pennsylvania. Deke mentions that they have a large VoIP project
at Penn which they refer to as a pilot despite having 800 production users.
They are using SER as a SIP proxy, Asterisk for voicemail, and the local IP
infrastructure for transport on campus. Until recently they had (traditional
PSTN) gateways for the local exchange carriers but recently have switched to
Level 3 for selected communities of test users, sending traffic completely
over IP to Level 3's network. There is a lot going on at Penn with VoIP
beyond the trunking being discussed today, and they would be happy to answer
any questions in the future.

Steve provides an overview of Penn's current implementation. They are located
in a dense urban area in Philadelphia, and have a dense wave division
multiplexing connection to a carrier hotel where they physically peer with
Level 3. The campus is spread out over a broad geographic area, so they added
a stand-alone edge proxy to facilitate the distribution of hardware. They
follow an end-to-end model for the media stream, which passes directly from
phones to the Level 3 session border controller. Penn has completed the
outbound peering testing using the commodity internet, and are testing the
inbound now. Steve says that overall they have had a very positive experience.

At several locations around campus, Penn operates network aggregation points,
which are environmentally controlled rooms with high-redundancy campus
backbone connections housing SER and Asterisk servers. The edge proxy
mentioned earlier is a Dell Poweredge server running RedHat Enterprise 4 and
OpenSER. This is their only OpenSER server, and was set up because at the
time SER did not support least cost routing for outbound calling while
OpenSER did. Steve says that they aren't necessarily going to continue to use
OpenSER or SER, but notes that they interoperate with no problems. The edge
proxy serves to provide a level of obscurity to hide their internal
addressing as well as a place to do LCR and route selection, address writing,
and other operations required by carriers. For example, peering with Level 3
requires address to be in the E.164 format. LCR is performed based on NPA NXX
area codes and exchanges. The North American Numbering Plan's website
provides a zip file that they reformatted and used to populate their LCR

For the Level 3 interoperability test, Penn performed the self-paced test
with the Web application. The portal allowed they to keep an itemized list of
things that needed to b addressed, which Steve found very useful. He notes
that they did not have any way of communicating with Level 3 during tests,
but Level 3 assigned an engineer to work with them over email which helped to
solve any problems, which he would recommend for others looking for support.
They completed the test over two months, with Penn's holiday break falling
during this time for an actual time of about 6 weeks.

They just began inbound testing, and have ported five numbers from Verizon to
Level 3 and are working on a configuration file for OpenSER. Steve notes that
they now own these numbers, and will have to handle situations such as DIDs
being unassigned. They are configuring their edge proxy to play a prerecorded
message or otherwise deal with these situations, which will hopefully allow
them to manage their number space more effectively and control moves, adds,
or changes on campus.

Penn has also developed an in-house provisioning tool for VoIP named PIPS.
They have to integrate ITSP into PIPS, such as the ability for DID assignment
and unassignment. They also need to have a way to determine if and what type
of calls can traverse the ITSP connections and which should use the local
gateway, and have to do this in a way that allows support staff to make
changes as well
as understand the impact of any changes on end users. They have added the ability to determine on a per-user basis if they can or cannot use the ITSP connection, in anticipation of possible HIPAA and CALEA compliance. Right now Penn is sending traffic from ten to fifteen end users through the connection to Level 3, and some previous echo and static issues have been eliminated and feedback has been positive.
Walt asks about testing, and if quality was examined or if testing was based
on completion only. Steve says that only completion was tested for various
scenarios, such as a call where the RPID says the call should be screened or
caller ID should be anonymous or where a digit-collection service like PIN
entry was in place. Call quality has only recently been tested due to some
issues with the local gateway. Traffic through Level 3 has been an

Walt also asks about secure traffic. Steve says that they are interested in
this, but have yet to apply any secure protocols to Level 3 traffic. Deke
says that they would like to use SRTP, but there is a lot of confusion
regarding HIPAA. He believes that voice calls which are not stored and
forwarded are not covered by HIPAA, but it might apply for access to

Candace asks about billing for the project. Steve says that billing is
addressed in the Level 3 contract, but he isn't the person to talk to about
this, but he could forward any questions to the finance department. Walt asks
about customer billing, and if Penn is doing pass-through billing. He also
wonders how they are dealing with billing for end-to-end IP calls with no
carrier. Deke says that they don't actually have any case for this right now,
as users cannot actually conduct end-to-end IP calls right now. When this
actually happens, they will deal with it. Right now they are preserving the
standard process of billing for calls and passing charges to end users. Steve
says they currently collect call detail records from the local Cisco gateways which contain well-defined start and stop records for every call. They have sent all-IP calls end-to-end but have yet to figure out how these fit into their business model.
Deke mentions that although they have 800 users, these users are not making
off-campus end-to-end IP calls right now. Currently the VoIP project is seen
as a Centrex replacement project for users, who are looking for Centrex-like
functionality for calling others with traditional phone sets; they are not
interested in IP-to-IP dialing or soft clients. Other functionality will be
introduced in the future, and it will be seen how this affects user's
day-to-day business tasks.

Garret asks if the monthly charges to IP users is the same as for Centrex users. Steve says that at first the VoIP pricing is less than Centrex charges but will be closer to Centrex pricing after six months. Deke says their goal is to keep the rate at or below the Centrex price, and to possibly drive it down over time.
Walt asks about inbound 800 calling. Steve says that they have not looked at
this yet, as no one has asked about it yet.

Candace asks about call trace back through the Level 3 connection. Steve says
that they are not doing this through Level 3 or through their local gateways,
but others have asked about this. With SER's accounting module it's easy to
keep track of calls, but users are used to pressing key sequence to enable
this and they have not been able to figure out a working solution for this.
asks if this is a local switch function, as signaling and caller ID
information is transmitted with the incoming number. Steve feels that they
probably could do this but haven't implemented it yet as they've had no
urgent need.

Following the questions from participants, Steve mentions that from a testing
point of view everything is going well and he's happy to answer any other
questions in the future. Walt mentions that Texas A&M is looking to move at
least half of their traffic to IP trunks and getting rid of half a dozen PRIs.

  • Notes from VoIP call - February 8, 2007, Garret Yoshimi, 02/22/2007

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