Telstra’s first-half profit has fallen by 6 per cent.

The telecom giant’s sales revenue has flatlined, and it has been hit hard by the impact of the NBN and writedown of its video streaming business.

Telstra’s net profit has come in at $1.7 billion for the first half, down from $1.8 billion this time last year.

But underlying profits — with one-off gains and losses stripped out — have risen 9.5 per cent to $2 billion.

Topline sales revenue in the highly aggressive market remained at $12.8 billion for the half.

The company has issued an interim dividend of 11 cents per share, down from 16 cents.

The company had earlier reported that a $3 billion earnings blackhole created by the NBN's erosion of traditional earnings streams made the previous dividend policies unsustainable.

Telstra chief executive Andrew Penn said the company is in a significant period of change – migrating to the NBN and facing competitive challenges, while also dealing with the accelerating pace of technological change and preparation for the transition to 5G.