In May 774, Byzantine Emperor Constantine V embarked on a major expedition against Bulgaria, led his field army on land and dispatched a fleet of 2000 ships carrying horsemen towards the Danube Delta.

The subsequent attack on Bulgaria failed since the imperial fleet had encountered contrary winds in the Black Sea.

Telerig then sent a secret emissary to Constantine that indicated his intention to flee Bulgaria and to seek refuge with the emperor and sought assurances of hospitality and a list of Byzantines who might help him.

In spite of his apparent success, Telerig found it necessary to flee to the new Byzantine emperor, Leo IV the Khazar, in 777.

The 17th-century Volga Bulgar compilation Ja'far Tarikh (a work of disputed authenticity) represents Dilyarek (Telerig) as the son of the former ruler Teles (Telets).