[Asterisk-Users] Analog Phones with Status Light Indicators

[Rich Adamson]

> On Thu, 2004-08-12 at 22:49, Rich Adamson wrote:
> > What you're looking for is key system functionality, and asterisk is a
> > pbx. Fully understand that many of the competitive products cross the
> > old line between key systems and pbx's by providing the most often
> > wanted features in a single box. Not likely to happen in the near term
> > with asterisk simply because the majority of the sip phones on the
> > market don't have the firmware support necessary to turn on/off the
> > led's for lines (or feature) buttons.
> 
> OK, so two questions:
> 
> a) Is there a cost effective 'pure key system' which can integrate 
> with asterisk to provide this solution?

Not that I'm aware of, but then I've made no attempt to track the
open source world for it either. Seems to be a fairly common requirement,
and for those that have worked in any large corporation, something that
is often required by executives and their assistants.

> b) What *do* the 6 'line' buttons on the Cisco 7960 and the polycom 
> IP600 and other similar phones actually do at the moment? And, what would
> it take to make these buttons/led's do what I want?

In the Cisco SIP-phone world, those keys were basically intended to
represent six pbx "extension" appearances, however there are a small 
number of other things that can be done with them. If one key is programmed 
as x1111 and the next key is programmed as x1112, one can see which 
line is ringing and answer the call appropriately.
 
> PS, sorry for being so thick, but I would like to understand this more fully.
> Also, would like to help make it happen, once I know what is involved...

In the old key system world, all pstn "lines" appeared on each telephone
instrument. It was rather simple to look at any phone and see that line #1
was in use, etc. Key systems were frequently deployed in small businesses
where the number of "lines" were limited.

When the number of pstn lines exceded the number of buttons on the phone,
or the number of phones was some relatively large quantity, a pbx was 
typically used instead of a key system. For pbx's, each phone is an 
"extension" (not a line) and logic within the pbx dictated which 
"extension" to send incoming pstn calls to. Other logic within the pbx 
handled what happened when a extension user picked up the phone and 
dialed "9" for an outside line (or whatever).

So, key systems associated a pstn line with a button on the phone, whereas
pbx's have never had a need to do that (due to automation, etc).

It was fairly common in the corporate environment to have a pbx handle all
of the pstn lines and all of the extensions. However, many executives wanted
their assistant to "see" when they were on the phone, so a large number of
these companies had small key systems behind their pbx's. It wasn't uncommon
for each executive to have their own key system (depending on the size of
the company).

Later on some of the pbx vendors smartened up and added features that would
provide executives with indicators on their phones showing when an "extension"
was in use. That cut the hell out of the key system sales. Some time 
after that Caller ID was actually added. :)

The key system manufacturers responded (as the cost of electronics continued
to decrease) by adding pbx functions to their key system product line. The
ability to transfer calls, call waiting, callerid, music on hold, etc, 
begin to appear.

At the present time, there really is no such thing as a key system verses
pbx (someone will likely argue that point). Now, what was a key system is
basically a small pbx with a limited number of pstn lines and a limited
number of extensions, and pbx's are simply larger (handles more lines and
more extensions, plus generally more features).

Asterisk and sip phones are patterned after the old pbx's, not key systems.

I don't know of any "standards" restrictions (in sip or anything else) that
would restrict adding key system functionality, but it would require logic
in both the sip phones and asterisk to truly implement it. That logic does
not exist in either the phones or asterisk today.

Since the majority of the sip phones on the market are closed-source, you
really can't add the key system functions to asterisk regardless of how
bright of a C programmer you might be. Additional logic is still needed
in the sip phones to handle turning the LED's on/off, etc.

Could there be "some" combination of phones, hardware and asterisk that
could be made to work like a key system? Probably, but no one on this list
has offered up reasonable solutions to do it. If there were such combinations,
it would likely be a major nightmare to support right now since each of the
software components are changing faster then what you could keep up with 
(eg, patches on top of patches, not to mention regression testing, etc).

The closed-source systems (eg, Cisco, Nortel, Avaya, Toshiba, 3com and 
other proprietary pbx products) have many of those functions implemented 
today, and those same companies are selling their products based on 
the "product differentiation" they can offer their customers. Cost is 
only one component of that, but a fairly important one.

Each of those companies have the expertise to move those functions to
their sip phone product lines in a heart-beat, but they'd be cutting their 
sales and profits by doing so today. (There is far more margin for them to 
sell a $50k closed system then there is in selling a relatively small 
number of sip phones.)

I can absolutely assure you there are employees in those companies that
are watching the marketplace and the advancement of sip (as well as other
standards), and when it makes business sense for them to trickle some of
those functions into their product lines, then will do so without a doubt.
But, it will be based on bottom line business economics and not on bunch
of people "asking" for features, etc.

In the mean time, selling asterisk against some of those products is
impossible "if" the customer is looking for certain features that only
exist in the closed-source pbx products. 

For those that have been selling telecomm for awhile, its fairly well known
the business purchasing decision is based primarily on "cost" followed by
"features". Its also fairly well understood that many businesses will
list a feature or two as "required" to ensure their favorite vendor is
selected. Asterisk can be sold into some of those accounts but not all.

Rich