Ofcom said strong competition had helped to drive down prices in real terms across the communications sector, with the exception of postal and some pay TV services.
The regulator's Cost and Value of Communications Services in the UK report said investment and innovation had delivered new networks and services, and increased quality and choice to consumers, concluding that: "Not only are consumers spending less on their communications services, they are generally getting more for their money."
The average monthly spend by individuals on mobile services fell by 23% in real terms between 2003 and 2012, from £24.99 to £19.10, while the volume of voice calls has more than doubled from 54 billion minutes per year to 125 billion, and SMS volumes have increased from 24 billion to 172 billion, the study found.
Some 92% of adults now use a mobile phone, while consumers' use of mobile data doubled between 2011 and 2012 alone.
The average amount spent on a residential fixed broadband connection has decreased by 48% over eight years, from £31.79 in 2004 to £16.38 per month in 2012.
This is against a backdrop of increased broadband take-up, from 6% in 2003 compared to 72% in 2013.
The average amount spent on landline services per month fell by 28% between 2003 and 2012, from £29.71 to £21.47.
Ofcom chief executive Ed Richards said: "The record in the last decade is good but we are determined to maintain focus on these important areas to ensure that communications markets continue to work in the best interests of consumers."