Competitors domain name which is trademarked (it is their business llc name as well). I verified this on the US Patent and Trademark Office website where it is classified as a service mark.

I found an 800 vanity number that matches the competitors business name perfectly (7 letter domain).

Their trademarked domain / business name implies a service and would be helpful for me to have a memorable phone number that implies the same service that I offer.

I would use this phone number on my website and advertising but it would be associated with my domain name which is completely different from their business name.

Would the competitor have a valid claim to sue me over this as legitimate trademark infringement?