[clug] VOIP auto dialer

Adrian Blake adrian.blake at ieee.org
Wed Mar 12 05:19:08 GMT 2008

OK, I need 2 sip addresses, although I could try to unplug one, Engin box, and plug in the other, computer, when I am on site. Yes 
I will need to look carefully as to how the existing Engin/linksys box is set up to cope with NAT etc.


steve jenkin wrote:
> Adrian Blake wrote on 12/3/08 2:57 PM:
>> I have a VOIP service through Engin. I want to have a computer auto
>> dial via my VOIP service, my mobile phone and play a message. The
>> message could be a security message or a message reporting on the
>> state of a network, etc
>> Will I need 2 SIP addresses or can I have two outgoing devices and
>> only one incoming, i.e. the normal phone?
>> Adrian
> Just to clarify - you want software on your computer, a softphone to do
> this.
> You're not being crazy and using a modem or some such :-)
> And sorry - don't know for sure. Never played with softphones :-(
> Obviously only one SIP device can register against an access number at a
> time - otherwise, how can the call distributor (?name?) route an
> incoming call correctly.  SIP devices have a TCP connection to their
> call distributor open all the time. And they chat over it reasonably
> often. This is used for call setup (and I'm guessing to notify of call
> termination).
> Copes with NAT just find - only the call distributor needs a public address.
> The actual SIP session - a phone call - is UDP from what I gather - and
> relies on STUN/TUNS to get between devices. Your firewall has to cope
> with in-bound UDP packets...
> I've run foul of both these at home :-(
> BTW, you seen the price of Engin shares since Seven Network bought in? 
> Went up, and gone down badly.
> cheers!
> steve

Adrian Blake
Molonglo Radio Observatory
University of Sydney
1152 Hoskinstown Rd
Bungendore 2621
ph. 02 62382262  mobile 0407 232 978

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