Ivr

What is IVR

Short for interactive voice response, a telephony technology in which someone uses a touch-tone telephone to interact with a database to acquire information from or enter data into the database. IVR technology does not require human interaction over the telephone as the user's interaction with the database is predetermined by what the IVR system will allow the user access to. For example, banks and credit card companies use IVR systems so that their customers can receive up-to-date account information instantly and easily without having to speak directly to a person. IVR technology is also used to gather information, as in the case of telephone surveys in which the user is prompted to answer questions by pushing the numbers on a touch-tone telephone.

Source : Webopedia

What to Use

IVR prompts can be recorded at Natural Voices. These prompts are not perfect as they do sound synthasised but they are good enough for home use. Another alternative is Cepstral Demo

To standardise on all voice prompts use Natural Voices: U.S English, Mike

Converting for Asterisk

The downloaded files are not compatible with Asterisk. You will need to convert them to a format that Asterisk can read.

sox foo-in.wav -t raw -r 8000 -s -w -c 1 foo-out.sln 

.. or for converting all files in a folder.

for a in *.wav; do  sox "$a" -t raw -r 8000 -s -w -c 1 `echo $a|sed "s/.wav/.sln/"` resample -ql; done