This is a service project of China Mobile. That is to say, in a certain area, such as Kunming, the members of an organization or team are all customers of Kunming Mobile, so the organization or team can apply for the group trumpet business of the organization or team members in Kunming Mobile Business Hall with a letter of introduction. After successful application, calls between members of the organization or team may be discounted (free of charge, depending on specific regulations). When dialing, you don't need to dial the whole number, just dial a few digits, etc. , you can get through. But only within the scope of Kunming. You can still get benefits after handling this connection service.
This is the meaning of "group trumpet large local network call".