Ring of the Ram: what kind of attack does it make?

The Ring of the Ram (DMG p. 193) states the following:

While wearing the ring, you can use an action to expend 1 to 3 of its charges to attack one creature you can see within 60 feet of you. The ring produces a spectral ram’s head and makes its attack roll with a +7 bonus.

What kind of attack roll is being made by the ring? Is it a melee or ranged attack? Furthermore, is it a weapon or spell attack?

Is there such a thing as a generic non-melee non-ranged attack in D&D5e? Or a melee or ranged attack that is neither a weapon or spell attack?