ATS7 not accepted by modem... Any alternative to this command ?

[Multicoder4002]

Hi

I would like to know if there's an alternative to ATS7 ?
My modem does not understand this command, so I removed it from the
registry settings for the modem (line CallSetupFailTimeout)...
But when I try to *disconnect* from the RAS connection (GPRS) the
modem does not accept any incoming AT commands, and it does not send
anything to output also...

Thank you !