Notes from talk on "IP Telephony - Hype or Reality" by Claudio Fleiner
from IBM's Zurich lab.

The talk gave the state-of-the-art in Voip and pointed out many of the
existing problems with it. Many of the issues are directly relevant to
ICEBERG. The main message seemed to be that there are several hard
problems to be solved with Voip. These have not been solved in any
satisfactory manner so far.

The slides of the presentation are at
<http://www.icsi.berkeley.edu/~fleiner/> 

State-of-the-art
~~~~~~~~~~~~~~~~

* Products:

  - teleconferencing products: Netmeeting, IBM, Vocaltec
  - gateway products: IBM, Vocaltec
  - gatekeeper products: datebeam, radvision, picturetel
  - proxies: IBM, Intel, Cisco
  - other products: routers with phone jacks, cards to connect POTS
    jack to a PC, cards to connect analog lines, ISDN, T1
    (e.g. Thor-2), telephone with ethernet connection.

* Standards:

  - H.323/H.245/H.225/H.235
  - SIP/SDP
  - RTP/RTCP
  - T.120 for data
  - LDAP for directory services

Problems with Voip
~~~~~~~~~~~~~~~~~~

The gist: security problems, billing, QoS, interoperation.

Interoperation problems
~~~~~~~~~~~~~~~~~~~~~~~

* Internetworking with PBX/PSTN. Call handling, call holding etc must
  be defined on both sides and must be made to interoperate.

* Many IP telephony products exist (MS Netmeeting, IBM Vocaltec). They
  provide different sets of features.

  - Some come with directory service support, some dont.
  - Some use standard signaling, some use non-standard.
  - None provide any real QoS.
  - None provide any real security mechanisms.

* Operation of naming/discovery/location protocols is not possible
  across firewalls. Proxies may provide the solution for this. But
  proxies usually provide only one signaling type (SIP/H.323).

* H.323 has too many loose options - makes interoperation of different
  products difficult.

* Protocols defined between different entities: gateways, gatekeepers,
  directory servers, SS7 entities. But this set of protocols does not
  cover all pairs of entities. No protocol defined for conversation
  between entities that belong to different administrative domains.

Problems with billing
~~~~~~~~~~~~~~~~~~~~~

* No centralized entity defined in any Voip protocol. Nor has a
  protocol been defined for the entities (gateways/gatekeepers) to
  talk to each other and work out a billing mechanism.

* Interoperation with PSTN, taking billing into account, makes it even
  more difficult.

* Standard problems of: security of billing, what to bill in the
  packet-switched world. These issues are more difficult to handle
  with conference calls.

Problems with providing QoS
~~~~~~~~~~~~~~~~~~~~~~~~~~~

* RSVP not scalable.

* Virtual Private Networks make QoS an even bigger problem.

* Approaches so far: differentiated services, splitting QoS traffic
  from normal traffic.

Problems with security
~~~~~~~~~~~~~~~~~~~~~~

* Directory service should be secure.

* Billing should be secure.

* Another problem with providing security is the interoperation with
  existing security mechanisms like kerberos.

Future Vision
~~~~~~~~~~~~~

* Telcos will move from voice n/w to packet n/w
* Permanent IP connection to homes
* All new PCs support video conferencing
* QoS networks for business users