Listening to SMS, which is send without any port number - J2ME

Hi,

I need a solution for the following problem:

I have a SMS Sender & Receiver MIDlet with MessageConnection created in Client mode for sending SMS to a particular destination on a particular port. This destination is sending back an ACK SMS without any port number set, to my device inbox. My MIDLet is listening on a same port number used for sending SMS. Problem is MIDlet is unable to listen & process this SMS. The message always goes & sits in the device inbox. Is there any way to listen to SMS without any port number? or route the SMS to the MIDlet?

Thank you very much!