[Asterisk-Users] Simple phone question

[Joe Greco]

> Okay, so I've got my "proof-of-concept" system working with soft SIP phones
> (SJlabs).  Now, if I want to buy hard phones, what do I use?  We have 8
> lines coming in to our building and we plan to use all 8.  Do we need 8-line
> phones to use all 8 lines?  If I have a multiline phone, will the different
> lines flash when there is an incoming call?  If so, how is this
> configured/controlled in asterisk?  Just trying to figure this stuff out.
> Any suggestions or help would be greatly appreciated.  Thanks again
> asterisk!

Having recently taken the plunge into this kind of stuff myself, let me
give you a few pointers.

If you're familiar with traditional small PBX's (Pana 1232, etc) then you
may be used to seeing some of the typical configurations where both lines
and extensions show up on a lampfield.  Many small businesses use this,
and people get used to being able to tell that Bob is on the phone because
the lamp next to his extension is lit, or that Line 4 is ringing.

That's a fancy implementation of a key system, at least in my opinion.

Most larger companies don't have phones like that, because you'd need
hundreds or thousands of extensions, and that's just not practical.  In
such systems, you may have a variety of methods for dealing with incoming
calls, such as Direct Inward Dial (you directly reach an extension by
dialing a PSTN number), or dialing into an IVR system, or dialing directly
in and getting into a queue, etc.

One of the key conceptual differences is that an "extension" is no longer
necessarily a physical phone...  there's no reason that multiple calls
can't all be routed to Extension 1000.

What happens depends on the technology.

If Extension 1000 is a Zap channel (i.e. an interface card that has an
RJ11 into which you plug a phone), that may not be able to receive more
than one call at a time (I'm not real clear on whether there are built-
in functions within Asterisk like call waiting for this situation).

If Extension 1000 is a SIP client, Asterisk simply offers it off to the
phone, and lets the phone worry about it.  From what I've seen, SIP
phones (hard or soft) deal with this by allowing you more than one call
per "line", but I've not worked with too many clients or phones.

Now, as far as your inbound dialtone, if you have 8 lines but they're all
on a hunt, logically you have one line capable of 8 simultaneous calls,
and I suggest that you frequently remind yourself of that.  If you have 8 
DID lines with 40 numbers attached to them, you have 40 lines capable of
8 simultaneous calls.  Etc.

What you're trying to accomplish is almost more important, however.

If you want to have an IVR system answer and say "Hi, thanks for calling
Foocorp, hit 1 for sales, 2 for accounting, or 9 for the company
directory", then you merely need to make all incoming lines ring into
that context (see extensions.conf), offer the menu, and then decide what
to do with each menu option.

For example, here we have a queue for general calls that rings several
extensions simultaneously.  Whoever picks up first gets the call.  The
other extensions cannot tell which extension picked up the call, cannot
tell which other extensions are busy, and cannot even tell that an
incoming line is in use (other than that it rang).

That may seem counterintuitive at first, but this system could be scaled
up to 90 phones without any modification (and that's merely a matter of
design choices we made).

SIP Multiline phones are a convenient way to meet more complex user
requirements.  Each line is essentially an extension.  For example, if
I want to log in to the sales queue, in addition to having my regular
extension, I can punch Line 2 and log that in to the queue.  The Line 1
indicator will then ring for calls to my primary extension and Line 2
will ring for sales calls.

The main way you would really need 8-line SIP phones is if each of the
8 incoming lines was for a different purpose AND you needed to have all
lines appear on all phones.

If, however, you can have Asterisk doing some management on your behalf
you may find that you only need one-line phones that have the ability
to deal with two simultaneous calls, or something like that.

Give us some details about what you want to do and how the system will
be used.

... JG
-- 
Joe Greco - sol.net Network Services - Milwaukee, WI - http://www.sol.net
"We call it the 'one bite at the apple' rule. Give me one chance [and] then I
won't contact you again." - Direct Marketing Ass'n position on e-mail spam(CNN)
With 24 million small businesses in the US alone, that's way too many apples.