Subject: [Sipping] comments on device requirements

From: Jiri Kuthan <[email-masked]>
Date: Mon, 23 Jun 2003 02:53:19 +0200

My apologies for commenting with a delay, better now than never:
in general I think it is a very useful document, which every SIP 
phone vendor should read well every morning.

There are some items I would prefer to be enhanced, dropped or changed 
in recommendation strength.

-Jiri

- NAT traversal capabilities should be complete, that's a very important one.
  in particular rport and comedia support is missing
- DNS/SRV fail-over -- I would suggest you explicitely mention, that 
  SIP phones must be able to use backup server referred to by DNS/SRV
  servers if they detect unresponsive primary for delivery of any
  requests
- I don't think MWI is a MUST; I get my voicemail messages delivered by
  e-mail and like that much better
- I'm not sure that SIP-17, obeying multiple 18x, should be mandated.
  I'm not even sure what a proper behaviour would be.  Sometimes so many
  18x are received that switching between them is quite confusing 
  for caller.
- SIP_20, fax support -- I don't buy it as a requirement; I like fax2email 
  better; visit www.efax.com
- I would not mandate SIP-22, _per-line_ DnD, either -- that's 
  a matter of taste, I like single-button global DnD better
- other thing I would like to have is a "deny" button for incoming
  calls -- every cell phone has it and very few SIP phones do
  (I don't really wish john.doe's call to ring to long if I am not
  interested in a conversation)
- sipsec-1 -- I would mention "including qop" which is frequently 
  broken in some implementations
- 3.17 "available behaviour" -- I don't think this set of requirement
  is to be put on phones; phones can go off-line, or their administrative
  interface can be unreachable -- I think these services are better
  placed in network

--
Jiri Kuthan            http://iptel.org/~jiri/  

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