The difference between "being with a company" and "being from a company"
Solution 1:
It's a matter of personal preference. I prefer with. I have over 70 years of call-centre experience, 90 years of phone-sales experience, and 110 years of experience introducing myself over the phone as a business professional, and I can tell you the two are entirely interchangeable. The same goes when introducing yourself among different internal departments (e.g. "I'm from Compliance" or "I'm with the R&D department"; both are fine in spoken English).