IVR (Interactive voice responce) is one of the most used PBX applications so you'll probably want your dialplan to take advantage of this feature. In order to do so, you must create a set of voice menus that can be played to the user as they navigate through the system. These voice menus are constructed from pre-recorded sound files, which can be obtained in several ways.
There are several sets of pre-recorded professional IVR sounds available from Digium at http://downloads.asterisk.org/pub/telephony/sounds/. They are used by the voicemail system as well as IVR so the core sounds should always be installed on your Asterisk system. We like to get the ".wav" format sounds, so that Asterisk can convert the sounds to the best quality format to send out to the user, when each sound is played. You should download the following files from the URL mentioned above:
asterisk-core-sounds-en-wav-current.tar.gz
asterisk-extra-sounds-en-wav-current.tar.gz
The core sounds were probably already installed by your version of Asterisk, when you built and installed it. You can check the /var/lib/asterisk/sounds directory to see if it is there and make sure that there are lots of sound files in the subdirectories such as "en". If the sound files aren't present, you can install them like this:
su
mkpath /var/lib/asterisk/sounds/en
cd /var/lib/asterisk/sounds/en
tar -xvzf .../asterisk-core-sounds-en-wav-current.tar.gz
If you need them, you must always install the extra sounds manually, as follows, after you've installed the core sounds:
su
cd /var/lib/asterisk/sounds/en
tar -xvzf .../asterisk-extra-sounds-en-wav-current.tar.gz
Instead of the Digium-supplied sounds, you may want to get the American female sounds file sounds-amer-fem-1.0-sln.tar.gz from Voice Vector at http://www.voicevector.com/Downloads.php. Follow their instructions to install it.
You can search the text indexes, provided with the sounds collections, to find the IVR menu sounds that you need. Once you find what you need (if you find what you need), you can string sound clips together like this:
exten => s,n,Playback(thank-you-for-calling&if-u-know-ext-dial)