The Liber Pontificalis mentions that he had been an anchorite, or hermit, monk prior to assuming office. According to the testimony of Irenaeus, he suffered a “glorious” martyrdom. Although most early popes are called martyrs by sources such as the Liber Pontificalis (dating to the 3rd century at the earliest), Telesphorus is the first to whom Irenaeus, writing considerably earlier (c. 180 AD), gives this title, thus making his martyrdom the earliest attested martyrdom of a pope after Peter.

Eusebius places the beginning of his pontificate in the twelfth year of the reign of Emperor Hadrian (128–129) and gives the date of his death as being in the first year of the reign of Antoninus Pius (138–139).

Credits: PA; Author: PA;

The tradition of Christmas Midnight Masses, the celebration of Easter on Sundays, the keeping of a seven-week Lent before Easter and the singing of the Gloria are usually attributed to his pontificate.

A fragment of a letter from Irenæus to Pope Victor I during the Easter controversy in the late 2nd century, also preserved by Eusebius, testifies that Telesphorus was one of the Roman bishops who always celebrated Easter on Sunday, rather than on other days of the week according to the calculation of the Jewish Passover.