Hi.

Currently I have Nortel PBX Option 61 connected to a cisco VoIP Gateway
using a T1/PRI ISDN interface to have calls to another Nortel PBX Option 61
connected to another router using ISDN as well. Nortel PBX boxes already had
the PSTN Connection (another T1/PRI ISDN).

Now we would like to have a failover to the PSTN in case there is no
bandwidth available on the network or for some reason the call cannot be
completed through the IP network.

1. It is better to do the failover on the Nortel PBX using some sort of
least cost routing (hunting) with the VoIP Trunk and the PSTN trunk and with
the correct digit manipulation?

2. Or it is better to have the VoIP Router to hairpin the call back to the
nortel PBX (as a new call) in order for the PBX to send the call out the
PSTN trunk. (in this case the router will do the digit manipulation
necessary). I know that this option will consume more DSP resources and
channels on the T1/PRI.


Any ideas? Suggestions?

Thanks,

[ Post a follow-up to this message ]

Sending for the second time.....

On 1/22/07, embeleco <embeleco@gmail.com> wrote:
>
> Hi.
>
> Currently I have Nortel PBX Option 61 connected to a cisco VoIP Gateway
> using a T1/PRI ISDN interface to have calls to another Nortel PBX Option 6
1
> connected to another router using ISDN as well. Nortel PBX boxes already h
ad
> the PSTN Connection (another T1/PRI ISDN).
>
> Now we would like to have a failover to the PSTN in case there is no
> bandwidth available on the network or for some reason the call cannot be
> completed through the IP network.
>
> 1. It is better to do the failover on the Nortel PBX using some sort of
> least cost routing (hunting) with the VoIP Trunk and the PSTN trunk and wi
th
> the correct digit manipulation?
>
> 2. Or it is better to have the VoIP Router to hairpin the call back to the
> nortel PBX (as a new call) in order for the PBX to send the call out the
> PSTN trunk. (in this case the router will do the digit manipulation
> necessary). I know that this option will consume more DSP resources and
> channels on the T1/PRI.
>
>
> Any ideas? Suggestions?
>
> Thanks,
>

[ Post a follow-up to this message ]

Create a preference 2 dial-peer to route the call out to the PSTN... but you
will need a gatekeeper to deny the call and route it out a different
interface.

You might be better off hairpinning it back to the PBX...



Jonathan

On 1/24/07, embeleco <embeleco@gmail.com> wrote:
>
> Sending for the second time.....
>
> On 1/22/07, embeleco <embeleco@gmail.com> wrote: 
>
>
>  ________________________________________
_______
> cisco-voip mailing list
> cisco-voip@puck.nether.net
> https://puck.nether.net/mailman/listinfo/cisco-voip
>
>
>

[ Post a follow-up to this message ]

Thanks Jonathan,

We are going to be using Gatekeepers as there would be more than two sites
involved in the toll-by-pass (probably more than 5). I was thinking of
hairpinning the call back to the nortel PBX using the same T1/PRI circuit
even though I know it will consume more DSP/B-Channels on the T1/PRI.

That is why I was thinking on doing the failover to the PSTN on the Nortel
Side completly because I was thinking that the cisco router can send an ISDN
Q.931 message saying that it cannot complete the call and with that message
the Nortel should be able to switch the call to the PSTN trunk and send it
accross the Telco. I know we can do that in CallManager.

Any comments?
-J


On 1/24/07, Jonathan Charles <jonvoip@gmail.com> wrote:
>
> Create a preference 2 dial-peer to route the call out to the PSTN... but
> you will need a gatekeeper to deny the call and route it out a different
> interface.
>
> You might be better off hairpinning it back to the PBX...
>
>
>
> Jonathan
>
> On 1/24/07, embeleco <embeleco@gmail.com> wrote:
> 
>

[ Post a follow-up to this message ]