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How long should it stay up for;?...

 
 
tony sayer
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      02-19-2013

Now thats got yer attention;!..

Anyone any idea how long a VoIP connection should stay connected for
lets say across a PABX thats on a wide area VPN circuit. Phone A rings B
B answers and thats it. How long might it stay connected for?..

And what if the connection cuts out briefly suppose either end will hang
up?.

Cheers...
--
Tony Sayer

 
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Gordon Henderson
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      02-19-2013
In article <(E-Mail Removed)>,
tony sayer <(E-Mail Removed)> wrote:
>
>Now thats got yer attention;!..
>
>Anyone any idea how long a VoIP connection should stay connected for
>lets say across a PABX thats on a wide area VPN circuit. Phone A rings B
>B answers and thats it. How long might it stay connected for?..


Forever. Unless there's some sort of absolute call time limit in the PABX,
or the Internet connection breaks.

>And what if the connection cuts out briefly suppose either end will hang
>up?.


It depends. A few seconds can be fine. Minutes less so.

Gordon
 
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David Woolley
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      02-19-2013
tony sayer wrote:
>
> Anyone any idea how long a VoIP connection should stay connected for
> lets say across a PABX thats on a wide area VPN circuit. Phone A rings B
> B answers and thats it. How long might it stay connected for?..


On A VPN, or on a public internet connection from an ISP who operates IP
addressing properly, for ever. Some ISPs apparently deliberately
shuffle the IP addresses from time to time, probably to frustrate
severs. VPNs may collapse under those circumstances, as well.

Why were you expecting any limit?

>
> And what if the connection cuts out briefly suppose either end will hang
> up?.
>

With default settings, Asterisk will tolerate a media stream outage of
60 seconds and some multiple of a minute for signalling stream outages.

 
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tony sayer
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      02-20-2013
In article <kg0piu$dld$(E-Mail Removed)>, David Woolley <(E-Mail Removed)
..demon.invalid> scribeth thus
>tony sayer wrote:
>>
>> Anyone any idea how long a VoIP connection should stay connected for
>> lets say across a PABX thats on a wide area VPN circuit. Phone A rings B
>> B answers and thats it. How long might it stay connected for?..

>
>On A VPN, or on a public internet connection from an ISP who operates IP
>addressing properly, for ever. Some ISPs apparently deliberately
>shuffle the IP addresses from time to time, probably to frustrate
>severs. VPNs may collapse under those circumstances, as well.
>
>Why were you expecting any limit?


Don't know .. just curious!..

>
>>
>> And what if the connection cuts out briefly suppose either end will hang
>> up?.
>>

>With default settings, Asterisk will tolerate a media stream outage of
>60 seconds and some multiple of a minute for signalling stream outages.
>


OK thanks...
--
Tony Sayer

 
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Phillip Helbig---undress to reply
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      02-20-2013
In article <(E-Mail Removed)>, tony sayer
<(E-Mail Removed)> writes:

> >> Anyone any idea how long a VoIP connection should stay connected for
> >> lets say across a PABX thats on a wide area VPN circuit. Phone A rings B
> >> B answers and thats it. How long might it stay connected for?..

> >
> >On A VPN, or on a public internet connection from an ISP who operates IP
> >addressing properly, for ever. Some ISPs apparently deliberately
> >shuffle the IP addresses from time to time, probably to frustrate
> >severs. VPNs may collapse under those circumstances, as well.


Historically, volatile internet addresses were used because the ISP had
many more customers than addresses. Since most were usually not
connected (back in the modem days), this made sense. Nowadays, many
people stay connected all the time. However, some ISP, understandably,
charged more for fixed IP addresses, so making all fixed---even if they
have as many addresses as customers---would mean losing this revenue.
However, it is also easier with addresses which are changed, since it
automatically weeds out those no longer in use. There are many
dynamic-DNS services; the best in my experience is
http://www.dynaccess.com which I've used for many years. It is no
problem to run servers on a volatile IP address.

 
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David Woolley
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      02-20-2013
Phillip Helbig---undress to reply wrote:

> However, it is also easier with addresses which are changed, since it
> automatically weeds out those no longer in use. There are many


Changing an address that is in active use does nothing to weed aout dead
addresses. Good practice is actually to reserve an address for some
time after the lease expires. If you have very few in reserve, you
still don't gain anything by changing them mid-session. I am pretty
sure it is done so that a premium can be charged for business accounts,
although a lot of business choose to use consumer accounts, because they
are cheaper.

> dynamic-DNS services; the best in my experience is
> http://www.dynaccess.com which I've used for many years. It is no
> problem to run servers on a volatile IP address.
>


I basically see dynamic DNS services as part of an arms race, where the
ISP tries to differentiate accounts, but the DNS services try to give
back the premium service.

In any case, mid-session changes in IP address still do disrupt VoIP
users, even with dynamic DNS. I've seen several reports from Asterisk
users with that problem.
 
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Stephen
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      02-20-2013
On Tue, 19 Feb 2013 14:35:52 +0000, tony sayer <(E-Mail Removed)>
wrote:

>
>Now thats got yer attention;!..
>
>Anyone any idea how long a VoIP connection should stay connected for
>lets say across a PABX thats on a wide area VPN circuit. Phone A rings B
>B answers and thats it. How long might it stay connected for?..
>

It may be simpler to look at it backwards - think about what makes the
connection drop?

>And what if the connection cuts out briefly suppose either end will hang
>up?.


Probably with some definition of "brief"

Most voice connections will have a session (or 2 uni directional
flows) between the 2 voice end points - lots of variations because
even now we still have lots of VoIP protocols for corporate systems
(and even more wierd control setups)

VoIP will have control connections to a "server" from each end (the
control stuff may be a session up throughout the call, or just during
setup, or intermittant during the call, and call and answer may be
different).

Losing specific signalling packets may drop a session immediately -
usually that is an issue at call setup

you sometimes get other devices in the various flows as well
- session border controllers often go inline in corporate or carrier
VoIP sessions, and may do NAT, send records to billing, mutate the
signalling / VoIP codec and so on.

Contact centres have other complications - the streams may be copied
to storage for recording, or to let supervisors listen in.

Timeouts usually come with defaults - and some systems let you change
them, but sub second to a few seconds for the audio, and subsecond to
minutes for the control connections.

Note most traffic disruptions are not as "easy" as "drop all traffic
both ways"
- maybe you lose packets in 1 direction for 200 mSec, but none in the
other for a short link,
- or the 2 directions fail but starting / ending at different times
- you get a sudden gap in packet arrival but all the packets do arrive
eventually (although they probably fall outside of the dejitter buffer
so dont do anything useful)
- a line drops momentarily and "no route" gets sent back to the source
and the IP / UDP / Voip stack gives up....

But anything in the flow with the concept of "session" may drop the
flow, or time out a cache entry that makes it drop. Home routers used
to good at this........

Likewise the control connections are often partly there to watch what
is happening and maybe kill broken or unwanted sessions
- eg your international or mobile call may have cost limits imposed,
- or the admin guy doesnt like you using up part of his limited pool
of WAN voice channels for too long.

>
>Cheers...

--
Regards

http://www.velocityreviews.com/forums/(E-Mail Removed) - replace xyz with ntl
 
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tony sayer
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      02-22-2013
Snipped...

>Likewise the control connections are often partly there to watch what
>is happening and maybe kill broken or unwanted sessions
>- eg your international or mobile call may have cost limits imposed,
>- or the admin guy doesnt like you using up part of his limited pool
>of WAN voice channels for too long.
>
>>
>>Cheers...


OK thanks for that all interesting stuff..

FWIW the original query was for a private wide area system on a VPN
basis..
--
Tony Sayer

 
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