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By suburban1
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Just researching VOIP at the moment. We have a main office with a 6 line Panasonic PABX. We have a number of mobile workers in satellite offices which have broadband connections. What we'd like is a gadget that will interface between our broadband connection in our main office and our PABX, such that the remote workers can use a "softphone" of some kind to make free calls via the broadband connection that will enter our PABX and ring an existing extension as per a normal incoming call. Is this possible, without having to change our PABX or existing handsets? We've experimented with Skype but it doesn't allow call transfers to other Skype users, plus we'd have to buy Skype phones for all our staff. We don't really want to go with a virtual PABX as we're stuck in a contract and our existing system is still quite new. Any advice appreciated.
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By VoipIT
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Hi suburban1,

Unfortunately you did not provide sufficient details in your original post to allow us to suggest an appropriate configuration that will meet your requirements. However, after saying that, I am gonna make an attempt at suggesting a few configurations that may suit your setup. I assume that you currently have 6 incoming exchange lines that are connected to your PABX and that these are 6 analogue lines (POTS) as opposed to ISDN-2, ISDN-30 or DASS circuits.

1. Convert all calls to VOIP

Port all your phone numbers to a VOIP provider and have all your incoming and outgoing calls delivered via your broadband connection. This will provide the maximum flexibility, since your PABX will be able to receive any mixture of VOIP originated and PSTN originated calls, limited only by your 6 incoming lines. In order to achieve this, you will need to purchase a VOIP gateway which will act as the interface between your VOIP provider and your PABX. The VOIP gateway accepts a LAN connection and has a number of FXO ports to provide connections to your PABX. Take a look at broadbandbuyer's website to see the list of VOIP gateways available. Or, you could take a look on Ebay to see what you can find (click here).

2. Mix VOIP and PSTN

Allocate a number of your PABX lines for PSTN originated calls and a smaller number for VOIP originated calls. With this solution you will only be able to handle a small number of VOIP calls, however, this will keep the cost down since you wont have to spend so much for the VOIP gateway. (In fact, you may be able to find small VOIP gateway devices designed specifically for PABXs which integrate 2 x FXO ports and a LAN port to allow you to share each incoming PABX line between VOIP and PSTN calls, hmmmm, that would be neat but I dont know if they exist). This wont be as flexible as option 1, since you will be allocating some PABX lines to PSTN only calls and some to VOIP only calls.

I hope this helps. If it does not, just let us know and I am sure that someone here should be able to help with more info.

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By WelshPaul
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The solution I'm describing will allow remote workers to have extensions on your existing PBX, delivered over their broadband connection. This means that existing PBX users will be able to simply dial their extension, and that the remote workers will also be able to dial other PBX users directly. Depending on how you do call transfers, you may also be able to transfer incoming calls between PBX users and remote workers. It's not simple though.

It will also allow remote workers to make calls to regular telephones direct from their site (without going through your PBX), will also allow them to accept direct incoming calls from regular telephones (again without going through your PBX).

You'll need a Obihai OBi110 (about £49) for each remote worker. This is a little gateway device that will be installed at your main office, each one connected to an extension line on your PBX, and also connected to your network switch.

You'll need a VoIP account for each remote worker, and a VoIP account for each Obihai OBi110. The easiest way to do this would be to take out the Voipfone Virtual PBX service. For a remote worker to "dial-in" to your existing PBX, they'd dial the Voipfone extension number for their Obihai OBi110. They'd then hear a dialtone on the PBX, and could dial accordingly as though they were directly connected. For a PBX user to call a remote worker, they'd just dial the PBX extension for the relevant remote worker. The Obihai OBi110 would be configured to dial the remote worker's VoIP phone and connect the call.

You'll also need enough upstream bandwidth on your internet connection for the number of concurrent calls you expect. Allow between 40kb/s to 110kb/s per call (dependent on your choice of codec). You may want to consider having a dedicated internet connection for VoIP traffic.

Setting up the Obihai OBi110's to do this isn't trivial. You'll either need to be prepared for a steep learning curve on VoIP, or pay for someone who knows what they're doing.

At the end of the day, it may just be simpler (and a cheaper start option) to have your remote workers *not* integrated with your PBX. Give them accounts on a Voipfone Virtual PBX so they can call each other and regular phones directly, and just have them call your main PBX number when they need to call in. It should be possible to configure your Panasonic PBX to allow head office incoming calls to be transferred to external numbers (such as your remote workers' Voipfone numbers), and Voipfone allows calls can be transferred in to your PBX from your remote workers.

I'd try out this scenario first with a single Voipfone account and a softphone (with USB headset). If all works OK, I'd then upgrade this account to a Virtual PBX and add others. I'd then upgrade the softphones to a good VoIP "hard"phone such as the Snom d715 (they are massively better than softphones!).

This solution isn't dependent on internet bandwidth at your head office, as the calls between HO and the remote workers are going over the regular phone network.

It's entirely possible that you may find that, despite being in a contract, it's *still* cheaper to switch wholesale to a Virtual PBX over time. If the call rates on Voipfone are massively cheaper than the contracted rates on your PBX, you could still win out even if with paying the monthly rate for your PBX. You can check this out at your leisure. If your current phone service provider can provide you with an online itemised bill, you could import this into an Excel spreadsheet and then run a comparison on what the calls would have costed with Voipfone, adding in any charges for Virtual PBX accounts.

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