You just create a Google business account. You then get yourself a Google VoIP P# with the appropriate area code and put that as the contact. If you really want to give it a sense of legitimacy, create a few Gmail accounts and give the business a rating… also rate a few other real businesses and don't rate the same real businesses with the same fake profiles. This sounds very complicated, but it really only takes about two hours. The great thing about attaching the phone numbers to Google business pages is that the caller ID will show up as the business name.
More than likely they won't even bother checking if you seem capable and interview well. I had applied to a ton of different places and wasn't getting very many interviews, but after I did some “creative” resume work, I was getting all kinds of calls.
As a note if they do call your “business” you should let it go to voice-mail and call them back after your pretty sure they aren't at work and leave a message. Realistically you should see if you have a friend who wouldn't mind being your boss if you don't think you can fake a different voice.
If you want to really really make it seem legitimate you can create a fake website to go with the business. Depending on how far you want to go you can either go ahead and lease a domain name or just use a crappy free website creator and just link it to your Google business page. This will take the longest of all the steps, but will really make your “business” look legitimate. Try to not use the ones that have a date stamp on the bottom. I guess you could always use a legitimate website and just hope they call the number on the Google business page. You could try and find a defunct website that you try and reach any of the contacts if none of them respond you should be golden. They're then going to have to reach out to the number you've provided.
You could always just be the lazy POS you really are and just tell the company that you're applying to that your previous employer is no longer in business, but where's the fun in that?