Switching from Data Mode to Command mode


I have a MC8790 modem.
I can establish a data connection to and from the MC8790 modem to a landline modem (US Robotics 5637) using AT commands (ATD , ATS0=1 etc.) using a simple terminal at each end. But I can not get from data mode to command mode on the MC8790 modem using “+++”, I have provided the appropriate 1 second guard times before and after sending +++. On the landline modem the +++ command works fine. The only way currently I can terminate a data call on the MC8790 modem is to close the modems AT serial port, as I can not get it out of data mode to hang-up the call correctly (this causes the MC8790 modem to reset/reboot). This method works but is not ideal.
I do have “3G Watcher” running, (to establish the connection to the mobile network) is this causing the problem?
Any help would be appreciated.


Send +++ characters with 1sec delay before & after to switch you UART to AT MODE, then send ATH to end your CALL.

The +++ character must send synchronously (at same time without intercharacter delay), you can write in notepad, then copy-paste to your terminal.



Thanks for the reply, but this is what I am doing that is not working.