Lately, all inclusive tariffs for mobile phone calls have become very popular in many countries. For a higher fixed base fee, you get 1000 or more minutes per month included, with no additional time-related costs.
On the other hand, there are still pre-paid cards with no base fee at all, but with very high costs per minute. Among friends or in a family, it often doesn’t make sense that everyone gets one of the more expensive tariff variants.
As a result, if two people with those two different tariff models want to talk to each other, it only makes sense if the all-inclusive person calls the other one, in order to avoid additional expenses.
If the pre-paid person wants to start the call however, the all-inclusive person should discard it and then call back. Only then no additional costs have to be paid. Unfortunately, this method has got several disadvantages. First, the all-inclusive person always has to be careful whether he should accept incoming calls or call back. Second, it is more work for both persons. And third, it takes quite some time until the call is established.
Auto Call Back
The process described above is automatically handled by Auto Call Back – if activated, the application discards calls from people in a special contacts group and then establishes a call back.
The all-inclusive-person has to start the application on his phone. Next, he simply puts all people from his contact database that should be called back into an auto call-back contacts group. Whenever a contact from this group now establishes a call, it is automatically discarded by the application. Afterwards, the number is immediately called back.
From the point of view of the pre-paid person, it’s equally easy to use. He builds the call to the all-inclusive person and then just waits until he can press the green key to answer the call-back.
Proof of concept prototype
Due to the limitations of the current public telephony API, incoming and ringing calls can’t be elegantly discarded due to phone security reasons – the call has to be owned by the application to control and cancel it. In order to own the call, the auto call-back application has to accept it first. This would usually result in the calling person having to pay a full minute, even if the call only lasted a few milliseconds.
To prevent this, the only option is to simulate a press of the red key. As a result, you have to make sure that calls do not get diverted to the mailbox if they are not accepted.
Also please note that this application was developed as a proof-of-concept and therefore is not as polished, feature-rich and bug free as you would expect from a full commercial application. It only concentrates on providing the automatic call-back feature and does not offer additional features like an invisible auto-start during the phone start-up.
The telephone features used by this application need to access several lower-level features of the phone and therefore require access rights that would only be available through Symbian Signed. In order to install the application on your phone, please sign it with your developer certificate or through the open signed process.
· Symbian S60 3rd Edition