What I see is that if you didn't do any modification to your cellphone it is not going to work...
The problem is that USB is a complete slave / master protocol, so in order for this to work, and your phone is usually a slave, and the adapter is a slave too. Even if your phone had host(master) capabilities, a driver for RS232 for your phone certainly does not exist.
In short, this means that the adapter only works to connect a computer to a RS232 device, and not the opposite.