Creating your own VOIP system

Hi everyone,
First of all, bare with me as i’m not native english speaker.

I am a apprentice junior software developer(18 weeks of experience) for a medium size company,
one of my assingment is to present how would my company go about creating thier own VOIP system. At the moment we are using Freshworks / Freshcaller. So exact task is to present a document with some details about how we gonna do it and what would be the cost, but this is where the problem starts. I’ve spent a whole day on researching VOIP and I am very confused:

this is what I understand so far:

  1. Rent a server(Linux based, cheaper)
  2. Load Asterisk on a that server
  3. Subscribe to some VOIP Gateway provider(To support landlines)
  4. Connect Asterisk with Gateway.
  5. Desktop client? can we design our own?
  6. It works!

we currently use 5 numbers, and Freshcaller last month cost us £80 - 166 incoming calls - 513 outgoing.

Can someone please give me some guidance on what I’ve got wrong, and maybe some bullet points of what I need if I missed something.


For that number of calls, I would consider a Raspberry Pi as your real hardwate. Asteriks needs Linux.

Although it is possible to use SP point to point, very few people do, so all youre external callswill need to go through a provider, not just those to old technology lines. I suspect your own system will only make sense if you make lots of internal calls (or transfer calls internally).

So you suggest to use RaspberryPi? we do some internal calls between tech support and sales aswell.

Could you please write how I wold go about doing this with RaspberryPi, I would really appriciate that.


Please note I haven’t use Raspberry Pi with Asterisk, or in a commercial environment, so wait for other answers.

Thanks, for reply.

so you are saying that all my points are mostly correct, but maybe renting a server would be an overkill?

If you rent a server, you arre probably renting a time share of a server, and if you are not careful, it might share out the time to someone else just at the wrong time, Also you are vulnerable to long and roundabout routing of traffic.

The first step is to actually determine what your business needs are for this system. Will it be hosted in the cloud or does it need to be on-premises? How many devices are there? Will NAT be an issue with X amount of devices if the server is in the cloud? What do you need for this server (CPU/RAM/HDD)?

That last will will be determined by what does this server need to do? Again, how many users/phones, how will they be connecting, do you need things like queues, ring groups, conference bridges, etc., etc. etc…

Well there’s more than just loading Asterisk on the server. You’ll need to make sure all the proper prereq’s are there and anything else you might need for the server based on the business needs.

Then there is the fact you’ll need to setup all the modules configs, your SIP endpoints and write all the dialplan for the needed call flow and features your business is going to require.

You’ll need a SIP Trunk provider because there are no landlines with SIP.

Are you referring to a softphone like Bria? I would look at existing commercial products versus creating your own.

As long as everything else was done properly, yes.

I strongly advise against using a RasPI for this. Get a real server, doesn’t matter if it’s bare metal or virtual but a RasPI is not something that should be used in a commercial/business environment as a PBX.

Thanks, for answer

Last question would be:

I need SIP Trunk not Voip gateway provider - and that’s just on my end, from there we can receive phone calls from clients that calling are calling from their land lines?

Of course. You’re getting them now with FreshCaller which would be done via SIP already. You realize that FreshDesk etc aren’t an actual phone company right? They just provide a SIP service for their customers.

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