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mrenos

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I would like to create a voip package ( hard - soft ).

Hello to all,
What i want to do is this : Create a "package" for my costumers so all of their calls go through voip. This means cheap and if it's possible free.
I would like to know is there any one that can tell me the hardware that i will need and also some sip servers that i can use to route my calls.

Thanks!
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grblades
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Cant you get your customers to use skype or similar?
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mrenos

ASKER

I want them to use there existing telephone installation with phone center and telephone devices.
So you have an existing PBX (telephone exchange) that you wish them to use?
I assume that it does not have VoIP functionality?
How many and why type of telephone lines do you have?
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ASKER

The number and the type depends from costumer to costumer.
Let's say for example the configuration from one of them.
This company has 5 ISDN lines and 4 PSTN.
Do they have a telephone exchange or do they just plug phones directly into the analogue lines?
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Yes, they do.
Well you could get a Sipura SPA-3000 device which will connect to an alogue interface on the exchange  and also to a SIP provider. You could configure the exchange to use this analogue line for outgoing calls if users use a specific prefix to get the outside line. However this approach will only give you a single simultaneous call over the internet. You could purchase additional SPA-3000's to get more simultaneous calls.

If you have a large office then you would need something like a PC running Asterisk and then a E1/T1 card in the asterisk box and interface it to a similar interface in your telephone exchange. This will give you a bank of 24/30 lines.

For the internet connectivity required to support VoIP I normally recomend a dedicated internet line. If you cant do this then you can use a router and prioritise the VoIP traffic but this can only be done for outbound data.
My previous comment assumed that you wanted to use your existing telephones for making the calls.
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ASKER

E1/T1 card is a card where you can connect digital and analog phone lines, the cost for a box running asterisk with a card like that ?
The internet line is ADSL 1Mbps/256Kbps up/down .
Voip routers prioritise the outbound data only, with the above internet bandwith will be ok to work with 24/30 lines ?
Asterisk is free and you just need a standard desktop spec PC to run it. A E1/T1 card such as the Digium TE110p (which I use incidentially) costs around £300 ($500).
You may need to buy an interface for your existing phone exchange aswell if you dont have a spare one in it.

Your ADSL lines upload bandwidth is the problem. If you use a typical low bandwidth codes such as gsm 256Kbps will only be able to support about 8 simultaneous calls. Even if you pay for a commercial low bandwidth codec such ad G723.1 you will only be able to support 12 calls.
Also bear in mind that ADSL is a shared service and therefore you are not guaranteed to get the full bandwidth all the time.

I went with a 512Kbps SDSL line with a low contention ratio. SDSL in the UK is more expensive but it gave us the ability to have more than 8 calls using gsm codec.
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My last question is : How can i connect this card with the existing PBX ?

Thanks.
You will need the existing PBX to have a spare E1/T1 interface. You then just connect the cards together and configure the existing PBX to send the call out of that interface if the users use a specific prefix for an outside line. Then for example if someone uses 9 for an outside line their call goes out the normal telephone interface but if they dial 8 the call gets sent onto asterisk which then sends the call over to the internet provider.
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grblades
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Ok. That was helpfull.
Thanks a lot.