Asterisk handling a small business

Chris Wood chris at
Tue Apr 8 08:48:53 MDT 2014

On Tue, Apr 8, 2014 at 5:14 AM, Dan Egli <ddavidegli at> wrote:
> Someone I talk to on a regular basis is getting ready to open his own
> company. The expected size of the company would be about 10-15 people once
> he finishes hiring, with more to follow in a year or two (he hopes). What
> he wants is to have all his phone calls and what not handled by Asterisk
> using IP based phones (obviously). I've talked with him a lot about this,
> but the points I could not remember dealt primarily with how the phone
> company would handle things.
> Supposing that you wish to have the possibility of half of these people
> (we'll say seven) placing calls or receiving calls at the same time. Under
> standard phone setups (POTS) that would require seven incoming lines. Is
> that going to be the case if all he buys is a DID number and internet
> service? I.e. does he have to tell the phone company to sell him multiple
> DID numbers in a roll down sequence? Or is simply having the phone call
> come to the system sufficient and then Asterisk handles it from there? I
> admit I have not looked at Asterisk myself (I'd love to, but I've got a few
> other things I really need to accomplish  before I start studying a
> VoIP/PBS setup in detail) so I don't know the answers. I tend to think that
> it's likely that he'd need multiple DID numbers and the roll down, even
> though it's all IP based, because it's likely the phone company that's
> going to generate the busy signal, and if they only have one DID number on
> file for you, then when a second person tries to call they're just going to
> get a busy signal (or voice mail if you have that service). But I honestly
> don't know for sure. I'm sure he'd also need to purchase one extra DID
> number, not in the roll down sequence, that he can configure to
> specifically be for the fax machine whose duties I'm sure Asterisk won't be
> able to assume (forward to the fax, sure, but actually answer as a fax and
> send/receive transmissions? Some how I doubt it.)

Generally speaking, you purchase/subscribe to SIP trunks to handle
calls.  The number of concurrent calls you want to handle is the
number of trunks you need.  The DID is based on the number of phone
numbers you want to have -- they will run across those trunks.  You
can have more DIDs than you have trunks.  You can have one DID and
multiple trunks (everybody has extensions instead of their own phone

Companies typically charge you for DIDs and then charge you for
trunks.  The DID charges vary a lot and can be more expensive than
they should be.

For DID and trunks, at my last company we used:

Fax can be obnoxious with VOIP.  I would recommend getting a copper
line from the local telco.  Maybe somebody on the list has the magic
sauce to make fax easy on voip.

> So, what exactly do I tell him to ask the TeleCo for? He's going to be in
> southern Utah most likely (i.e. St. George area) so it's likely going to be
> Qwest or AT&T, unless you can get phone/DID service from someone like
> McCloud USA, which I honestly don't know. He plans this to be a heavy IP
> business, so I don't think Comcast would be such a good idea, with the
> monthly bandwidth caps they like to place on downloads and uploads (has
> anyone heard of Comcast offering more than 1 mbit upload speeds?), not to
> mention their 250 GB/Mo download limit.

Those limits on Comcast are for residential use.  Your friend will
want a business grade internet account.  Which company supplies the
SIP service can be independent of the company providing the internet
service.  I would get the most reliable ISP he can get in his area and
then do the VOIP separate if the ISP isn't competitive.

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