PBX-to-PBX call over IP Network

[NAGISWAREN2]

Hi All,

I have a task to do with VOIP, but generally have no idea on how to accomplish it. So here is the scenario.

We have 3 sites, all running on thier own Panasonic PBX system

Site A : extension start with 1xx

Site B: extension start with 2xx

Site C : extention start with 3xx

Every site , have 3 - 4 PSTN line which connected to the PBX. Outbound & inbound call made via this PSTN line. Call between this 3 sites, also made over PSTN line, which involve huge cost. Now my boss wanted to cut this cost, with below requirement.

1) Call between branches should be made over IP network, just by dialing extension number. Eq, from Site A, just dial 2xx to call Site B user.

2) Should not involve major changes on VOICE setup, perhaps stick with current PBX system and Analog Phone

3) Incoming call to Site A, must be able to transfer to Site B over IP network

Currently this 3 site is connected via IPSec VPN, with below device.

Site A : Cisco 2811

Site B&C: Cisco 1841

So what extra hardware&software&interface module needed to accomplish this task? Can anyone share me the full idea, with example configuration. Sorry but i have zero  knowledge in VOIP, and would like learn about it.

Regards,

Nagis       

[paolo bevilacqua]

The best approach is that you engage a reputable consultant, or UC certified Cisco partner, that will do design and implementation. If you try to do yoursel, you will loose much time, and not get sure results.

[NAGISWAREN2]

Anyone else? I have search through internet, some saying get fxo/fxs card on cisco and connect to pbx. Other said get E&M card.. Just couldnt get clear picture and guidline


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[will.alvord · Accepted solution]

The 1841's don't support voice but at least the 2811 does. I know nothing about your PBX platform so don't know if you'll need any additional hardware other than 2 new ISR's and pvdm's. Obviously your current platforms have PSTN gateways but unsure if they support SIP/323 to CUBE so can't tell you if you would need to migrate the PSTN connectivity to the ISR'S or what the inter-connectivity would look like.

Previous post is correct. In order for you not to lose time and to ensure that your project is successful, you need to engage a vendor. You can shadow this vendor and use this as a learning opportunity though if that's your worry.


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[NAGISWAREN2]

Thanks,

Anyway, my boss wish to me to setup on my own. FYI, we still stick with PSTN connected to PBX system, but allow PBX-toPBX call.

Changing to Cisco 2811 wouldn't be a problem as I have stock in hand. I will get back to you on the model of current PBX.

Regards,

Nagis

[NAGISWAREN2]

Hi All,

My Office using Panasonic TES824 key system, which doesnt support PRI or E&M card. I believe it can only support FXO/FXS , correct me if im wrong. For now, there is no plan of making SIP call over internet. It will be on Phase 2. Now in Phase 1, just need to allow PBX-to-PBX call over IP Network, to cut branch-branch call cost.

My boss wish me to setup this, so that i can learn new stuff.

Regards,

Nagis

[NAGISWAREN2]

Anybody?


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[will.alvord]

I can't speak for the Panasonic key system or its config, but in theory you can physically connect to an fxo/s interface on your ISR where dial-peers (inbound pots peer, outbound voip peer) would be configured to create the SIP/H.323 call leg to the remote ISR where you'd have similar dial-peers configured (inbound voip, outbound pots) pointing to the analog interface to that key system port.  You will need DSP's on each ISR, but not much with only 3-4 POTS at each site.  Use the DSP calculator once you have your ISR model's decided on as well as how many analog connections per site, whether you'll be using g711 or doing transcoding, etc.  Troubleshooting will be fun as you'll be troubleshooing inbound POTS to PBX, analog connection to ISR, VoIP site to site, and back to PBX on the other end, possibly back to POTS at the other end if you're planning for TEHO.  You've got a lot of troubleshooting points in there.  All in all, it's a pretty complicated setup even though it seems very simple at a high level.

Since you're using this as a learning opportunity, go ahead and pickup a copy of the voice gateways and gatekeepers book as well.  Most if not all of the content is available online, but it'll save you some time having it all in one place.

good luck

[NAGISWAREN2]

Hi will,

Thanks for usefull info. I have 3 Cisco 2811 with PVDM2-16 in hand.

Should I buy VIC2-2FXO and VIC2-2FXS inerface card to achieve this?

As my understanding, we use FXO/FXS so that, from PBX view, CIsco ISR will be an extension number, and from Cisco ISR view, PBX will be an extension number. Am I correct?

If this going to be the setup, can you provide me confguration guidline on ISR router for Both site? Million Thanks.

Regards,

Nagis

[will.alvord]

Based on your explanation, I would go with FXO on the 2811's connected to FXS interfaces on your PBX's.  Your understanding is essentially correct.  It'll be a typical PLAR setup.

Also based on your explanation, I understand that you would like to use this as a learning opportunity.  Ready to copy and paste configs are not going to help you accomplish that goal.  I have already pointed you toward the gateways and gatekeepers book (http://www.ciscopress.com/store/cisco-voice-gateways-and-gatekeepers-9781587052583).  If you find that it's missing something, please post back here.  Check the index for FXO, dial-peer, digit manipulation, and probably PLAR and then read those sections.  Should be all you need.

[jaschulz]

Great advice on this thread. If you're looking for a sample configuration here is one if you plan to use connection trunk.

http://www.cisco.com/en/US/tech/tk1077/technologies_configuration_example09186a00800afd65.shtml

[NAGISWAREN2]

Hi will,

Thanks. Anyway do i still need fxs on cisco 2811? I will go through the document and start my setup. I will post here if anything.

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[will.alvord]

I would go with FXO on the routers and FXS on the PBX's but if you already have FXO PBX interfaces then that would factor in. No sense having to replace hardware. For your purposes (essentially 1 for 1 analog port extensions across your WAN), you could go either way. I was just sharing what I would do. Just remember that your router interfaces will be the opposite of your PBX interfaces.


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