Cheap PBX + GSM Module

Dear Friends,

I’m trying to build a pbx system to work with 2 gsm channels with the following features:

Office Phones
Outgoing calls to nacional landline or internacional landline/mobile via VOIP
Outgoing calls to nacional mobile via GSM
Inbound calls via PSTN, forward to GSM possibility

Mobile Phones
Outgoing calls to nacional mobile with prefixes xx and xx via PBX GSM
Outgoing calls to internacional landline/mobile via PBX VOIP

Can you give me some advices for what should have better performance and cheaper?
You think that I should use some ready made pbx and gsm module or build my own pbx with asterisk?

Thank you for your help.

In your country, are mobile numbers easily recognizable, like in the UK (most national numbers starting with 7) or are they mixed in with landline numbers, like the USA?

What is you level of technical expertise?

A USA type answer to the first question may mean that you need a support contract to maintain the list of mobile phone number prefixes.

The other possible national issue is that there may be regulations to discourage the use of non-mobile mobile network terminals, with a preference for direct lines to the mobile network’s fixed infrastructure. In particular, having fixed terminals with high duty cycles will eat into the local cell tower’s capacity.

The current UK position seems to be that it is illegal to resell service through such devices, but it is legal to use them for traffic to or from your company.

Hello David,

Thanks for your reply.

I’m in Portugal, mobile numbers start by 9 and landline starts by 2.

I don’t have any knowledge of pbx or asterisk, I do have some knowledge of Linux and vps servers.

What I want is to choose the best route according with the origin and destination.
We don’t have any laws against that, what I need to know is if it is technically possible and what minimal budget I will need.


of course, you can use sangoma GSM+asterisk or cheaper solution: GSM (Dinstar gateway)gateway+asterisk.