The Freedom class (also known as the Pioneer class early in its development), was pre-Federation starship of the Earth Starfleet, launched circa the 2140s. Sometime between 2145 and 2150, one ship of this class, the USS Franklin, became the first Earth vessel to reach warp 4. The Freedom class was designated as an explorer frigate. (Star Trek Beyond, Star Trek Online)
The Franklin, and perhaps other vessels of the class, remained in service through the Earth-Romulan War and were later absorbed into the Federation Starfleet, continuing to serve in the early years of the United Federation of Planets. (Star Trek Beyond)
In the early 25th century, the design was upgraded, and new tier 6 Freedom-class vessels were launched. (Star Trek Online)