I posted this picture on twitter, and got some DMs and questions as to how we use that setup to power the Hotels.ng call-center. Here is a short description.
Hotels.ng used to use a bunch of mobile phones to power our call-center. As we reached 200+ calls/day, it became unfeasible to continue like that. There are many expensive call-center solutions, but we always have to watch our expenses and could not get any of those. Then one day, I saw this advert that CcHub was selling Raspberry Pis, and it hit me.
The raspberry pi is a tiny linux based computer that is just about as large as a mobile phone. It turns out that there is this call-center software called Asterisk that can be adapted to run on the Raspberry pi.
Asterisk is an extremely powerful call-center software that allows you do things like manage call queues, set customized ringtones, forward calls from one person to another, and importantly, integrate with your CRM (so when you receive a call, you see who is calling you).
The way it works is that you connect a router (the D-Link) above, to the raspberry (after loading Asterisk on it). You then put the sim-cards for all your lines into the router (and optionally, connect antennas to it for a better signal).
The raspberry is connected via ethernet to your router (e.g a swift modem). Your laptops are connected to the router also (and you install a software phone on all the laptops).
When a call comes in, it enters the 3g dongle, who passes it on to Asterisk running on the raspberry pi. It is then placed on the local network and forwarded to one of the computers. The way we have it — some particular numbers ring on some phone (e.g the numbers our hotel partners have ring on the hotel relationship desks only), while customer calls ring on all laptops on the reservation desks.
When a laptop makes a call, depending on the laptop, it will route it through a particular sim card.
This system also allows us record calls (for quality assurance) and to know which laptop has picked the most calls. It also allows us control the phone credit spend (over N200k/month!) and make sure the phones are not being mis-used.
If you have a call-center, you should try something similar!