Legal Question in Business Law in California

Probably. A lot depends upon the caller's current relationship with the "customer" and the nature and purpose of the call. For example, if the purpose of the call were to collect an unpaid bill, I'd say it was "debt collection," not "solicitation." However, by and large, most calls made by a prospective seller to a prospective buyer would have at least some measure of intent to obtain (additional) business, and hence fall under the heading of "solicitation" even if the caller isn't a salesperson and the overall theme isn't buy, buy, buy.