FAQ What services fall short and why 

 - Why do "destination-in-charge" services fall short of reclaiming the majority of lost calls?

The main drawback of "destination-in-charge" services is that in many cases, as one often experiences, they do not end up in an actual call. Even in cases when a call is actually made, it often originates from a carrier different than that of the original caller resulting in loss of revenue to original carriers. The reason for this is that in many cases the destination is less motivated to complete the call than the originating caller. In many cases, destination may ignore caller's efforts, be reluctant to complete the call at his expense, or choose to communicate with caller through a different channel, such as email or a different carrier.

Moreover, public sentiment in many countries has now turned against once very popular voice-mail service. There are countries where leaving a voice-mail message is considered an impolite burdening on the called party. In other places, it has become an annoying nuisance many try to avoid. It is a fact that many users choose not to install voice-mail service for their incoming calls, and many others refrain from leaving messages when encountering an unsuccessful call attempt.

- Several companies offer new call back services. Why do these services fall short of reclaiming the majority of lost calls?

The major drawback of those call back services is their being non-synchronized, in the sense that at the time destination becomes available/reachable and the notification is sent (e.g. by SMS), the original caller may be unreachable, and in such case at the time he receives this notification it may already be outdated or irrelevant. In other cases the SMS may be noticed and read long after being received, having the same effect of irrelevance.

One additional drawback of some of these services is that the user is just notified, but not actually prompted to complete the call. Completing the call requires an active decision and additional effort on part of the caller, which in many cases is too much to ask at the specific time the notification is received. Caller may put off the call and then forget all about it, or retry in a time when destination is again unreachable.
On-Q Telecom Systems Co., Inc.