Motorola, the second biggest mobile phone maker, faces attacks in both the low and high ends of the US market, according to a report by Goldman Sachs and Wolff Olins, the brand consultancy.

The company, already under pressure because of falling margins and the departure of a key senior executive, is being challenged in the low-cost market by service providers because it has failed to establish strong brand loyalty, the report says.

At the same time, it suggests Motorola also faces a threat in the higher margin, high end of the market from manufacturers that have developed differentiated products such as Nokia, Sony Ericsson, Research in Motion (which makes the iconic BlackBerry) and potentially Apple (which is due to launch its iPhone this year).

The report based on a survey of 8,800 mobile phone users in the US, United Kingdom, China and India – confirms that US consumers see little differentiation between handset brands and show little interest in leaving their service provider to gain a more attractive handset.

Charlie Stott, from Wolff Olins, said: “Cellphone operators are currently winning in the US because they dominate distribution and reduce handset manufacturers’ differentiation.

“The operators have a great opportunity. If Verizon Wireless and Cingular were to do more to build an emotional bond with consumers, we could see the entire relationship owned by the service providers.”

Outside of the US, the survey also suggests that Motorola will struggle. Brantley Thompson from Goldman Sachs said: “Motorola has failed to differentiate through building strong emotional bonds with consumers. Its focus on design and fashion did not translate into stronger loyalty, and as a result it has been left vulnerable to the fashion cycle.”

This month Ron Garriques, head of Motorola’s mobile phone division and the executive responsible for the launch of Motorola’s now ageing Razr handset, quit to join Dell, where he will run the PC maker’s consumer operations.