sim300 not able to send and receive the message

sim 300 gsm modem is not able to send the message nor is able to receive any message from the android phone. The message is send but android phone gets the message as "message format not supported"...sim 900A is able to send the required messages using the same sim card.. ....when I put the same sim card in the smart (android) phone then the sim card is able to send the message.ands a proper message is displayed on the another smart phone..

when I change the sim card then I am able to send the message and required message is displayed using sim300 modem. what may be the problem..??
plz help..

Try to check the character set currently set in your GSM modem. I am sure sure what is causing this issue but it happens with android phones somehow.
check char set with : AT+CSCS?
change char set with : AT+CSCS="UCS2"
and see if that solves your problem.