Is this an existing ECS modem used before?
If it is, power off the modem, check the status of the line/ctl and vryoff.
Power the modem back on then vryon the line with the reset parm.
Hopefully that’s all it is.
If it doesn’t work, test the phone line into the modem by unplugging the line and plugging it into a phone. Check for dial tone and call your cell for reception.
Could be your settings are not correct.
Here is a couple of links that might help you out.
Having testet wiring a.o. you may use cmd
to verify the connection