I worked for a agency, they always left my client unattended. She called me this morning because she was left stranded. She is bed ridden. Made numerous calls to emergency number. I went to help her. I was fired for insubordination for going. She has since switched agencies. Now the new company wants to hire me, can I go work for them or does the no competition clause stop me?
But if you've been fired from Company A you are free to work with whomever you choose via Company B.
I would read the employee handbook from your previous company just to be sure. If you are in contact with clients from your previous company and you tell them that you're with another company thus encouraging them to move their business to the new company I think you can get sued and/or fined by your previous company.
I am not an expert in Work Law either. Good luck!