When I worked at companies with self-service plans, we'd direct them there and say that we can't provide provide them enterprise service for now, until their company grows or their budget grows. When we didn't have self-service, we were just polite and that's all we could do.

Sometimes you'll have commercial/digital reps that handle high volume, low revenue customers. The company may also have a self-service/credit card swipe product option, or a free tier, or a support-only option.

There are also different teams.

At my company, we sell deals between $25k and $1.2m/y. You obviously get very different salespeople taking those calls.

Super junior salespeople promoted from SDRs train on the $25k-$40k; most salespeople handle midmarket deals up to maybe $200k; and the very best salespeople get the enterprise leads.