Problem:
When discussing life cycle, we generally refer to a product more than to a company.
Thus, we can not really say that Nokia is in the maturity stage. Some of Nokia's products may be.
Regarding the three companies (N95 from NOKIA. LG and SAMSUNG) mentioned in your example, we need to compare the same (or very close) product offered by the three companies and then discuss why or why not there are price differences among them.
Can you tell me what we mean by product differentiation and what is known as "Unique selling proposition"?