How should I organize my company's phone numbers?

Maybe the title is not the best to describe my question. We are a team that we want to create/organize some startups under our company name.
Suppose you have this scenario. Our company is named Main Company and has as products, other websites/products/companies e.g. First, Second, Third.

That means that First is made by Company. Like Windows are made by Microsoft.

I will be in this situation in a little while, having 2 products made by my main Company. Those two products First, Second are separated companies/websites/products from Main Company even though that are under Main Company.

My question is how should I organize my telephone numbers?

One possible solution is to use only one phone number for the Main Company, First and Second. The auto operator will give them the chance to press 1 for the Main Company, 2 for the First and number 3 for ther Second.

The other possible solution is to use 3 different numbers. One for the Main Company, one for the First and the third for the Second company.

What do you suggest us to do?

Also, can you suggest me some websites that offer phone numbers without phone line, I say about those services that you forward the number to your mobile phone. I need localized numbers like for UK, France, Germany, US.

I would strongly recommend looking into getting an internet phone services in the countries you are looking to do business in.

The great thing about the internet phones is that you can be almost anywhere in the world to place and receive calls.

Additionally I'd look at setting up something like Asterisk PBX, which has capabilities to forward to the external phone Now in addition to that I would very strongly suggest that you have someone who speaks German, French and English because people calling a local number expect to be answered in local language.