The telecommunications industry deputy ombudsman says phone and internet service providers need to give clear information to potential customers.

The ombudsman's office received around 150,000 complaints in the last financial year, almost 50 per cent more than in the previous year.

Just under 14,000 complaints were about mobile phone premium services, with many people saying they had not asked for them or were not able to unsubscribe.

Deputy ombudsman Simon Cleary says clear information about service plans is important.

"It seems to us that the information that consumers are given before they enter into the subscription services has to be clear," he said.

"It's a fundamental principle. [It] has to be clear so that consumers can make informed decisions about what they're purchasing."

The Communications Alliance says phone and internet service providers are trying to improve the service they offer to customers.

The chief executive of the Alliance, Anne Hurley, says she is not surprised by the figures.

"They're not totally unexpected, although disappointing, because we've had research recently which shows that communications services are increasingly viewed as being essential to people's lives. So there's a greater degree of expectation," she said.

"As an industry, our challenge is to manage these rising expectations and to find ways to respond so that customer satisfaction is improved."