IVR or Interactive Voice Response service operates through pre-specified numbers that banks advertise to their customers. Customer's make a call at the IVR number and are usually greeted by a stored electronic message followed by a menu of different options. Customers can choose options by pressing the corresponding number in their keypads, and are then read out the corresponding information, mostly using a text to speech program.

Mobile banking based on IVR has some major limitations that they can be used only for Enquiry based services. Also, IVR is more expensive as compared to other channels as it involves making a voice call which is generally more expensive than sending an SMS or making data transfer (as in WAP or Standalone clients).

One way to enable IVR is by deploying a PBX system that can host IVR dial plans. Banks looking to go the low cost way should consider evaluating Asterisk , which is an open source Linux PBX system

Asterisk, due to its open source nature has caught on in a big way and is being sold as an PBX solutions by quite a few companies commercially. However there has been considerable noise on multiple Asterisk related forums over the stability of Asterisk based systems. Companies planning to use Asterisk for their IVR solutions should certainly do a rigorous evaluation of its capabilities before committing their long term future on it.