Is there a company that will create a custom, voice recording for us
to use on our business' telephone automated-attendant outgoing
message?

Hi dmm,

There is a large industry based around the provision of custom voice
recordings for telephone and other messages.

You will find many such businesses listed in the Google Web Directory
under the following categories:

Business > Advertising > Media Production > On Hold Services
http://directory.google.com/Top/Business/Advertising/Media_Production/On_Hold_Services/

Business > Business Services > AudioVisual > Production > Audio
http://directory.google.com/Top/Business/Business_Services/AudioVisual/Production/Audio/

Business > Industries > Arts and Entertainment > Media Production >
Voice Talent > Production Companies
http://directory.google.com/Top/Business/Industries/Arts_and_Entertainment/Media_Production/Voice_Talent/Production_Companies/

If you are on a tight budget, you may wish to contact voice talent
freelancers, many of whom will deliver their voice recordings by email
and have demonstration samples on their websites. They are included in
the following Google Web Directory categories:

Business > Industries > Arts and Entertainment > Media Production >
Voice Talent > Male
http://directory.google.com/Top/Business/Industries/Arts_and_Entertainment/Media_Production/Voice_Talent/Male/

Business > Industries > Arts and Entertainment > Media Production >
Voice Talent > Female
http://directory.google.com/Top/Business/Industries/Arts_and_Entertainment/Media_Production/Voice_Talent/Female/


Google search strategy:

voiceovers
://www.google.com/search?q=voiceovers&sa=Google+Search&cat=&hl=en


Regards,
eiffel-ga