Hey Danielle,
We understand that some company put some restrictions in their company network.
The 3G/4G is a good solution.
With our experience, we can say that almost every provider works correctly.
Be careful to use a business account like Orange Business otherwise it will not work.
Here you can find a list of compatible provider :
SFR Business
ORANGE BUSINESS
BOUYGUES Entreprise
SOSH
And the last is more about an international and universal provider :
We hope that this answer can help you 