problems in interfacing of GSM mobile with 8051

hi!!
wish you a very happy new year to all of you
i am doing a hobby project of sending sms through Nokia E71 with 8051 using AT command.I successfully able to send sms from the mobile through hyperterminal or trying to make a call (ATD 98541*****).The same commands were also successfully sent from 8051 to hyperterminal.But when I connect the mobile with the 8051 nothing happens.As the mobile comes with an USB port therefore the connection is done as follows:

1.Using MAX232 the voltage level of 8051 is shifted to RS232 level.
2.The RS232 port is connected to a RS232 to USB converter.
3.The USB port comes with four pins D+,D-,Vcc and GND.As RS232 to USB converter module is USB bus powered hence the power for the module has been given from an rps source of 5V by cutting the usb cable to red(Vcc) and black(GND) cable.
4.The rest two cables of the module ie D+(green) and D-(white) is connected to the mobile's USB cable with D+ and D-.
5.for handshaking CTS and RTS point of the RS232 port also shorted.

I am not getting whats wrong is going on,Kindly help!!

ankur1403 said:

1.Using MAX232 the voltage level of 8051 is shifted to RS232 level.
2.The RS232 port is connected to a RS232 to USB converter.

Click to expand...

Why are you using MAX232?
Which USB Converter Chip are you using?

It would be better that you post the schematic of your circuit for better understanding...

Regards,
Saqib

I have got my wrong point.The 8051 has no USB hosting capability.Nokia E71 is having usb data cable only and which also act as a slave.The best way is to change my mobile phone having a serial port data cable.Can any body suggest the best and cheapest current model?