Before Voice over IP, there was callback
A recent post by Julian Bleecker on how people will devise complicated systems to find a way to communicate reminded me of the time I worked in a callback company.
In areas where owning a cell phone is not routine — for economic reasons, predominantly — it is not uncommon for a stranger to ask another stranger to borrow their handset to make a call. This happened to Francois on a trip somewhere and he, being a nice guy, agreed and handed over his phone. Only he thought this stranger was going to just go ahead and make a call. Instead the stranger dismantled Francois’ phone — removed the back, spilled the battery out and popped out the SIM card and then popped his own SIM card in there, reassembled the phone and made a bunch of calls in rapid succession, hanging up on each one after the first ring or two. (Mobile Phone Usage Idiom — No. 1)
While I worked there, I experienced a lot of so called hacks both to prevent callback to operate and to fight these restrictions. I had to designed some of these hacks to keep the service operating in some countries. Let’s first explain how callback works.
Callback is based on the following principle: instead on making one call, make 3 calls with the help of a distant machine. On the downside, calling somebody can be seen as a hassle but on the plus side, you can make calls for much more cheaper (depending on where you are located).
How does callback works (the original system)
- You contact a callback company
- They create a account for you with the following information
- the number you need to call, which is uniquely assigned to you
- the number where you want to make the call from
- You call the number assigned to you
- You let it ring (generally once is enough)
- You hang up before anybody picks up
- The company (which recognized you based on the number you called) calls you back
- You answer the call and get a prompt to dial your destination number
- The company puts you “in relation” with this number
- Once you hang up, the company will have billed you for 2 calls: once for the call from the company to you and once for the call from the company to your destination number
An example of how it works
Person A lives in Angola and wants to call Person B who lives in France. This kind of call are usually really expensive (more than $1/min). Person A decides to signup with a callback company (like United World Telecom the one I worked for). Person A account main information would look something like that
- Callback Number: +1 305 555 1234
- Source Number : +244 123 456 789
Now Person A wants to call Person B whose number is + 33 9 12 34 56 78. Person A will need to do the following:
- Person A calls the number +1 305 555 1234, let it rings once and hang up (cost = none)
- The company receives the call on a group of lines dedicated to receiving these call ( like 10-15 lines dedicated and matched to hundreds or thousands of phone numbers). The phone number +1 305 555 1234 can be thought of as being a “virtual” phone number, there is actually no physical line dedicated to this particular number. Along with the call, the telecom operators along the way are passing along the phone number in a format that can be captured by the callback company.
- Once the phone number is captured, the callback company will look up in its database for the phone number called (here 305 555 1234)
- The callback number is associated to the corresponding source number
- The callback system picks up a line, calls the number +244 123 456 789 and wait for the person to pick up
- The callback system picks up another line, calls the number +33 9 12 34 56 78 and link the two lines on its system so that Person A and Person B can talk to each other.
- Once the call is finished, Person A can end the distant part of the call with a key combination and redial another number or hang up
- On the callback company side, the two calls are added up and charged to Person A
Cost (as of 2002)
Option A: Direct Call from Angola to France: > $1
Option B : Same Call using callback
- Trigger call: Free
- Call from US to Angola: approx. $0.40/ min
- Call from US to France : approx $0.05/min
- Total: $0.45
Next, I will describe some of the features (speed dials,…) and how they can sometimes serve other really important functions that the ones they were originally designed for.