TCP server on HL8548 - transparent mode

I’m trying to switch from Motorola H24 modem to HL8548. I need to setup a TCP server that allows for transparent binary data transmission over the TCP socket.
In case of H24 it was called Online Data Mode. The H24 has one BULK interface for AT commands, and the other interface (BULK) for data.
I’m trying to accomplish the same on HL8548 but I’m stuck right now.
I’m able to open a TCP listening socket, and the remote host can connect with the modem, but I cannot see the data that the host sends to the modem. The AT+KTCPRCV and AT+KTCPSND commands are of no use for me as I want to open a direct data mode, so I can use some other endpoints (beside the AT control endpoints) to get and send the data.
I thought that the AT+KTCPSTART is all what I need but it gives me an CME 910 ERROR. It seems that this command does not work for TCP servers.
Is is true?
Does this modem have an transparent data mode like the ODM in H24?
If not, than this is a BIG problem for me.
Can I somehow get it to work?

Best regards,

Success, I get it to work, it was an error on my side. I used wrong session ID in the AT+KTCPSTART command.
Now it works as expexcted.
Best regards,