Graham joined Siemens in 1978 as a graduate trainee and held posts in the central marketing, sales and commercial functions. A secondment to the Far East followed, with involvement in developing new business in China.

A brief sojourn outside of Siemens as Sales and Marketing Director of Torch Telecom ended in 1997, and he returned to Siemens Communications as Sales & Commercial Director. In 1999, the decision was made to merge the Sales and Marketing functions of the business, with Graham taking the helm as Director of the combined organisation.

In March 2002, Siemens Communications brought two parts of its Enterprise business closer together, by combining Enterprise Sales and Marketing and the Customer Service Division into one Enterprise Networks business. Graham became its Managing Director until becoming MD of the overall business in October 2002.