Small Office Outbound only calls

[solsagan]

Hi,

I am wondering if someone one can give me some assistance regarding a direction to go with VoIP.

The scenario:
We are a small company that will be expanding in the near future. We have a spare 6144/640 adsl laying around and would like to use that for VoIP. At the moment we would only like to make outgoing calls. We would like to give the users Soft Phones and headsets to use from their laptops when they are in the office. Because this is only outbound calls, we don't really care for transferring calls between users or for users to call each other. We are hoping to get about 10 simultaneous outbound calls for the users.

Now my questions are:
* Do we require any additional hardware?
* Is it possible to create a single SIP account that all users can use (also what steps should I follow to create these accounts)?
* Some suggestions for a service provider?
* How many simultaneous calls can be made on the adsl line?
* Will caller ID be enabled with outbound calls?

At a later stage we will look into setting up an Asterisk server in house to facilitate inbound calls.

Any help will be appreciated.

Thanks

 

[gmza]

1. No you don't need additional hardware, but may need to ensure that your softphones support the G.729a codec. Only commercial softphones support this,not the free ones.
2. Yes, you can use a SIP account (e.g. Switch Telecom "Business VoIP Trunk" service), with the strict proviso that only one of the phones will ever receive incoming and the remainder continue to be used purely for outbound.
3. Switch Telecom (www.switchtel.co.za / 087 550 0000). [Disclaimer: I am affiliated, therefore my opinion is biased.]
4. Approximately 11 calls, assuming G.729a codec. Working on 42.4kb/s at the ATM layer of the ADSL, 640 / 42.4 == 15, however, I never suggest trying to run the link at more than 75% capacity as you need to leave margin for signalling and the reality is that ADSL seldom performs at 100%, even after overheads have been taken into consideration. 11 calls is 73% of the theoretical 15 call limit.
5. Caller ID is enabled by default, however, as with a Telkom line or a Cell Phone, you have the choice to block it if you so wish.

With Asterisk, you can enable IAX2 trunking. This will allow much higher simultaneous call capacity (up to 48 simultaneous calls at a safe margin of 69.6% of the theoretical maximum).