Saving USB cell modem dialog to a file

I have a ZTE MF190 USB stick on a Raspberry Pi. I run it with wvdial and it works fine. I want to log the signal strength. The appropriate AT command is AT +ZRSSI. When I insert this into wvdial.conf as part of the modem init strings and run wvdial at the terminal I get to see the output. I want to know the signal strength at a remote unit. I would like to be able to echo or redirect the init dialog to a file ......