How to perform automation testing on IVR application

IVR (Interactive Voice Response) Systems depend on DTMF digits, or tones, as inputs from the users and in turn presents a menu for banking, hospitality, voice mail, and other automated applications. When calling an IVR system from any interface, the user is asked to send DTMF digits in response to prompts. The IVR system may have several sequences and may require either single DTMF digit responses or several DTMF digit responses (i.e. the credit card number).

So how to automate these type of applications and what are the tools we have to use for automation.

complete steps required.

Thanks in advance.