Subject: [Sip] Callerprefs: Mobility tag

From: "Mary Barnes" <[email-masked]>
Date: Tue, 22 Apr 2003 12:50:40 -0500

In section 9.9, the mobility tag is described as "indicates whether the
device is fixed, wireless or somewhere in-between", however, there is no
definition for the somewhere in-between.  

So, my initial reaction would be to reword this as "indicates whether the
device is fixed or wireless", but then I got to thinking about what could
have been meant by some in-between and I think there might be some value in
defining some of those now.  

One term I had considered was "nomadic" as the "in-between".  But, then I
also got to thinking that perhaps "WiFi" is a good example of the
"in-between".  The usefulness of these really depends upon how they
would/could be used.  The one example I saw in the usecases draft was around
wanting to contact someone only on their mobile phone.  The inverse of this
could be that you absolutely don't want to contact them on their mobile
phone, but would want to contact them on anything else or perhaps only if
they're "fixed" or "WiFi". "Nomadic" might be useful for scenarios whereby
one's network connectivity is via tunneling, thus it's indicative not being
reachable at the "fixed" device (eg. the hard SIP client), but you are
available on your soft SIP client working from home.   I haven't thought
this all the way through, but I do think additional terms could be extremely
useful.

Mary H. Barnes
[email-masked]

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From: Paul Kyzivat <[email-masked]>
Date: Tue, 22 Apr 2003 17:45:14 -0400

I've always had trouble with the semantics of this feature. All the 
examples I can think of for using it really depend of coincidental 
association between mobility and other features.

For instance, *why* would I prefer to call someone on their fixed phone 
rather than their mobile phone?

- because use of the mobile phone is expensive?

- because I know the fixed phone is in a particular location
   and I only want to reach them if they are there.

Neither of these are really directly related to the fixed nature of the 
phone.

I think I asked Jonathan about this and he felt it should be kept 
because it had been around for a long time and we didn't have 
justification for removing it. Personally I think it could just go away.

	Paul

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From: Henning Schulzrinne <[email-masked]>
Date: Tue, 22 Apr 2003 21:50:43 -0400

I think this is useful. Yes, having something like "don't call if it 
costs extra" or "don't call if the person is in a car or meeting" would 
be better, but until everybody uses RPIDS, 'no mobile phone' is a pretty 
good approximation and actually implementable. (In European countries, 
the *caller* pays more for mobile calls, so this is a real concern. And 
mobile is indeed the distinction that matters, not something else.)

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From: Jonathan Rosenberg <[email-masked]>
Date: Wed, 23 Apr 2003 02:59:17 -0400

Well, practically speaking, people tell me all the time to "call me on 
my mobile". Caller preferences would allow me to do that without needing 
to have two numbers for that person.

Now, addressing Mary's main point, about adding other definitions for 
mobility. I don't want this to be a technology definition - i.e., 3g 
being different than 2g being different that WiFi. I think the essential 
aspect of it is whether there is a fixed poitn of attachment to the 
network or not As such, it is my preference to just remove the "in 
between" bit. Here is the new text:

\item[Summary of the media feature indicated by this tag:] The
mobility feature tag indicates whether the device is fixed (meaning
that it is associated with a fixed point of contact with the network),
or mobile (meaning that it is not associated with a fixed point of
contact). Note that cordless phones are fixed, not mobile, based on
this definition.

-Jonathan R.

Henning Schulzrinne wrote:
>> For instance, *why* would I prefer to call someone on their fixed 
>> phone rather than their mobile phone?
>>
>> Neither of these are really directly related to the fixed nature of 
>> the phone.
>>
>>> definition for the somewhere in-between. So, my initial reaction 
>>> would be to reword this as "indicates whether the
>>> defining some of those now. One term I had considered was "nomadic" 
>>> as the "in-between".  But, then I

-- 
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