Simple IP telephony between head office & 3 branch

Unanswered Question
Apr 23rd, 2008


I need some information and configuration link to setup H.O with 3 Branch already connected via VPN for IP telephony using ATA 186/188. This is just a starting of the project and do not want to setup any voice gateway & call manager initially.

I want to setup ATA at both the ends and connect analog phone to dial out to these locations.

I have this problem too.
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Sushil Kumar Katre Wed, 04/23/2008 - 03:57


As far as my understanding of ATA goes you can use H.323 on ATA for making calls without callmanaer.

However H.323 being a peer to peer protocol you won't be having communication between all the endpoints.

What's possible -

ATA -------- ATA

What's not possible

ATA1 ---------- ATA2


| ----------- ATA3

In the above setup ATA2 can be defined as peer so users at ATA1 can talk to ATA2 and vice versa. However since ATA3 can not be defined as a peer on ATA1, users on ATA1 can not dial to ATA3.

If you can let me know the overall number of users at each location we can think of some low cost design using CallManager Express.

-> Sushil

shoebwk Wed, 04/23/2008 - 04:05

Dear Sushil,

Thanks for the reply. Here are the details

1. All 3 branches connects to HO Via VPN. The link is DSL with 2MB bandwidth

2. one or two phone number at each branches is enough.

3. HO will have maximum of 3 IP telephony.

So i think the requirement is very minimal and since there is no cisco equipment now, i was looking for the ATA solution. But as you said this concept will not work.

i will be glad if you can provide me with cheapest solution



Sushil Kumar Katre Wed, 04/23/2008 - 04:11

Bare minimum what I can think is a Cisco 1861 router at the HO which supports 8 phones. Or else 2801 which supports 24 phones I guess.

If you are looking for a basic telephony setup why don't you look at Open PBX solution - Asterisk [linux based], 3CX [Windows Based].

You can download the 3CX SIP IP Soft Phone and install 3CX/Asterisk PBX on a PC/Server at the HO and the SIP IP SoftPhones would register to the central PBX.

How much would you be investing on this solution - 0$.

-> Sushil

shoebwk Wed, 04/23/2008 - 05:51

Hi Sushil,

I have attached the diagram and placed 1860 too. let me know is this correct and what else or which part# of 1860 i would require. Does it still require Call manager Express?.

The requirement is in proposal phase, i have to design, create BOM and present it to the Management then i can giveyou exact investment.

Could you provide me the components required for my requirement then i can estimate the cost?.

I would also check the Open PBX solution



Sushil Kumar Katre Wed, 04/23/2008 - 20:17


I was going through the consting of 1861 and 2801 routers and found that 1861 is more costly as compared to 2801.

Reason - It comes with CME, CUE, FXO, FXS interfaces.

Part numbers -

C1861-UC-4FXO-K9 - Cisco 1861, 8-user CME, CUE, Phone Licenses, 4 PSTN trunks (FXO), 4 Analog ports (FXS), 8 PoE ports, 1 HWIC slot for WAN

C1861-UC-2BRI-K9 - Cisco 1861, 8-user CME, CUE, Phone Licenses, 2 BRI trunks (BRI), 4 Analog ports (FXS), 8 PoE ports, 1 HWIC slot for WAN

I would suggest you to go for 2801 router at the HO.

Part Number -

CISCO2801-CCME/K9 - 2801 Voice Bundle w/ PVDM2-8,FL-CCME-24, SP Serv,128F/256D

All the phones at the remote location would register to the cenral CME. In case the IPconnectivity is lost between the phone and the CME the phones would be dead.

There is no need to have CME at all the locations. Have a centralized CME.

-> Sushil

Paolo Bevilacqua Wed, 04/23/2008 - 04:46

You can use linksys ata or ip phones. These allow dialing by IP and do not need a call manager.

However that a poor solution that really doesn't solve most needs so if your customer wants to do thing properly, he will have to buy a small router or uc500 for PBX.

Sushil Kumar Katre Wed, 04/23/2008 - 04:49

Hi Paolo,

What about the Open PBX solution. I have seen Asterisk providing many feature and functionality and looking at the setup they don't have more than 10 phones.

I would personally go for Open PBX.

Can you throw some light on that.

-> Sushil

Paolo Bevilacqua Wed, 04/23/2008 - 23:54

Hi, asterisk takes time to install, configure and learn, and to make a proper installation requires a dedicated server. Also when used with cisco phones the results are quite good to use with asterisk neither.

So if you get a second hand router like 2610XM or 1761V, you will spend less, and have a more robust and performing solution.

shoebwk Sun, 05/04/2008 - 00:28

Hi Sushil

I am also looking for 3cx solutions too. Is it possible to install 3CX at all the location and and let all the soft PBX talks to each other or it only support 1 PBX in the network

Sushil Kumar Katre Sun, 05/04/2008 - 19:25

Yes, you can have communication between multiple 3CXs.

Trunk needs to be configured between all the 3CXs and appropriate call routing should be configured.

-> Sushil


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