[Linux-aus] SIP

David Newall davidn at davidnewall.com
Thu Jul 4 04:15:21 EST 2013

On 03/07/13 22:27, David Lyon wrote:
> the impression that I get from those in my business circles is
> that they don't mind paying for telephone services.
> Where you see their point is on the receiving side of telephone calls.
> If 'anybody' can make free voip calls, then anybody will call. I'm
> meaning telephone canvassors/telemarketers here.

This is a very interesting argument, and somewhat persuasive on first 

Yet, unlike PSTN, you can't call every possible SIP address because 
there are a near infinity of them.  On PSTN you have a low-cost per call 
in a limited range of guessable numbers; via SIP it's zero-cost per call 
but an infinite and unguessable range.  At only a few dollars per hour, 
the human cost of calling dominates regardless of PSTN or VoIP.  On 
second thoughts I think you could convince your business associates that 
their fear of telemarket calls is exaggerated.  With only minimal 
decrease in cost to the enemy, It's unlikely to get worse than it is now.

As to difficulties configuring SIP phones and servers.  I've not done 
this but I can see that it's of a similar complexity to configuring 
email clients and servers; from which one might expect that most people 
will use a third-party SIP service to avoid maintaining their own 
server; and those service providers will give a few lines of 
configuration to put into your SIP phones, just as email providers give 
a few lines of configuration for your mail client.

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