This is a good case study of JV that never really worked as expected. One of the most interesting pieces of information was the fact that Sony was reluctant to link the handsets to the rest of its products which are very successful, fearing that Ericsson would had been benefited. This is also a very good example of how companies seeks to develop synergies based on their core competence. Sony has a great range of unique resources and core competences which should be linked to the handset.
It is quite interesting that when this JV was established the handset industry was not linked to any of other products by Sony.
Some articles for the full story: http://www.bbc.co.uk/news/business-15473954; http://www.bbc.co.uk/news/business-15285258