How to use a PC headset to make calls on a PBX line?


For short: this is what I would like to do: Use a headset connected to my PC to make and receive calls using a PBX line (connected to my PC or a server).

This might be a though question to get it explained. But I'll try.

This is the situation. At the university we all have fixed lines, connected to a PBX central I guess. At least we use "Siemens HiCom" Phonesets. I live in Belgium.

What I would like to do is use a headset connected to my PC to make outbound calls using my fixed phone's line. And preferably receive incoming calls as well.

I am a network and system administrator but we do not have any control over the telephone part. It's a completye different department that is managing that.

The options that I see is setting this up on my own PC or setting up a small server that has an outbound line connected to it, which I connect to over IP with my softphone on the PC.

But because I'm a complete newbie to everything that is VoIP related I don't know how to set ip up.

1. Is it possible on your own PC?

2. If so, what (hardware)card do you need and what software?

3. If I would set it up on a server what are the options? Asterix or Office Comm. Server? And what hardware needs to be in that machine to be able to use the fixed line?

4. Can it be just an ordinary PSTN modem card? Or do I need to buy special hardwware cards to give it an outbound line?

I realize of course I can just buy a headset for the fixed phone. But it IS really pricy and sooner or later we will be rolling out a VoIP system university wide.

I hope it's explained clearly enough. Otherwise just ask me.

Thanks in advance.
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1-4. actually it depends on your requirements.

if you only want to receive and dial voice call from your PC. then
PC = Voice Modem + Headphone Mic +  Software (on winxp: start -> run -> type dialer and enter). you may find many other dialers on internet

But if you need some advanced / professional features, like recording / monitoring, some automation etc ... then Asterisk will help you.

Server = Asterisk + FXO card (i.e. TDM400P)
PC = SIP Software + Headphone Mic

gert5142Author Commented:
So are you saying there is a way to connect the existing PBX line that I have to my PC and then use a headset connected to the PC as your phone to make outbound calls and receive incoming calls?

What kind of hardware card do you need for that? A regular modem card does not work with a PBX line right?

Furthermore: also a way to do both (connect it to the PC and leave the actual phone also working)?

Davis McCarnOwnerCommented:
1) If you have high speed internet, have you considered a MajicJack.  It will let you use your headset and give you unlimited callling in North America for $19.95 per year; but, you would have a different phone number?
2) There are devices which plug into the handset cable on your Siemens phones that are then generally used to allow a wireless headset to answer and place calls.  If you look for one which lets you plug in your own headset, you could then connect it to the PC if you have HDAudio in the system. has one of the largest selections on the planet.
Other than that, Siemens may have a PC interface for your PBX; but, you would need to know the model of the PBX, not the handsets and you have it exactly right; you need to match the signalling protocols of the PBX so you cannot use any standard phone devices.
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gert5142Author Commented:
Hi Davis,

Thanks for tour comment. I took a look at the Magic Jack but I'm not sure if that works in Europe/Belgium as well and if it would work with a PBX line. Do you think so?

Also I took a look at the hellodirect website. But since I'm not really into telephony technology I wouldn't know how to find a thing like you mentioned. And once again would it work in Europe as well?

Th last thing you mentioned you mean a SIEMENS hardware card that you can insert into your PC and then connect with the PBX line?

Davis McCarnOwnerCommented:
No, MagiJack is really only good for calling the US and Canada; though it will work great from Europe to USA/Canada and only needs a decent internet connection to work.
I don't know what phones you have now; but, the Optipoint E phone seems to work with most Hicom systems AND IT HAS A SLOT for adapters.  The analog adapter will let you use a voice-modem which lets you use your headset, a standard cordless phone which will let you wander at will, a fax machine, or a bluetooth phone which ought to let you use anything. 
You still need to know what the main PBX is and you'll need your phone guys to set it up for you.  Maybe you already have a phone with  an adapter slot?
gert5142Author Commented:
I don't know if I have an adaptor slot. But I don't think so. They are SIEMENS HiCom Set 551 T25FD Phones (P/N 51A3002). I have been looking to find some kind of manual of the phone but that seems to be impossible to find on the internet or the SIEMENS website. Any idea where I could find it?

Is it correct that a PBX line is a completely different thing than a PSTN (normal landline)? So a headset has to be either for PBX or for PSTN phone? I was hoping that a headset existed that you could just plug in between your handset and the phone with an RJ-45 connector and as such usable for both? You would then just intercept the sound/voice that comes from and goes to your phone. Any idea if that exists and what type of device I would need for that?

Davis McCarnOwnerCommented:
PBX phones use a proprietary communications protocol and have to in order to add features like intercom, etc.  The also carry the power for the handset in a way that is specific for each phone system.  PSTN or POTS (Plain Old Telephone System) devices won't work and could damage the PBX.
The standard connector for the handset (curly cable) is an RJ12 and they are uniform, meaning there are hundreds of devices which will plug in series with tthe handset and let you be the earpiece and microphone.
$55 U.S.:
Generally; though, you still have to go pick up the existing handset unless you also get something like this:
Please note that I do not claim these two work with each other, OK?  HelloDirect will help you choose if you call them.
Your set was sold primarilly in continental europe and I got a lot of hits in German, Czech, etc. Googling the 551T25.  It does have the adapter connection on the bottom and there are adapters like the analog one available.

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gert5142Author Commented:
So far, I think I know enough. Thanks for your answer.
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