Problem While i'm receiving data from external in data mode

Hello Everyone,
I would like to ask you about an a problem i’m encountering nowday, i’m developing an open AT application for GSM Modem, i want to convey voice through the modem.
The problem is when i’m in data mode and when i receive data from the external application (voice) in order to send it through the modem, during this moment i can’t send anything to the external application, why?
I can send to the external application something just after it send me all the data (voice message) in other word just after DLE Etx (end of transmission).

This problem is only when i’m in data mode receiving data from the external application, if the application doesn’t send me the data and i’m in data mode i can send to it something.
I wish you understand my question.
if you have solution, could you please tell me what can i do?

Best regards

It’s not at all clear what you’re trying to do here.

Have you discussed this with your local Distributor?

I think you will find it much easier to discuss face-to-face - possibly also without the English language barrier?