TPG's executive chairman David Teoh says he is "disappointed" the competition watchdog is taking so long to approve a planned $10 billion merger with Vodafone as the telco faces shrinking margins as a result of the National Broadband Network.

The telecommunications company's net profit for the first half was down 76.3 per cent to $47.4 million and revenue fell 1.5 per cent to $1.24 billion. Earnings (before interest, tax, depreciation, amortisation and impairment) increased 1.7 per cent to $420 million.

TPG Telecom has criticised the pricing of the entry-level NBN plans.

A major blow for TPG was stopping its mobile network rollout, a decision the telco blames on the government's ban on its vendor partner, tech giant Huawei, for the 5G network. This resulted in a $227.4 million impairment charge in the results. Excluding this expense, and $4.4 million in one-off transaction costs that form part of the company's plans to merge with Vodafone, underlying profit increased 3.2 per cent to $225.7 million.

Mr Teoh announced plans to merge with the mobile-focused telco in August and has since been waiting for the Australian Competition and Consumer Commission to approve the deal. In December, the ACCC delayed a decision citing concerns about the tie-up and the need for more information.