Problem with I 14 phone and Vonage

I have the T Mobile 5G wifi box and a land line through Vonage…If I call the Vonage number at home from  my I Phone, the cell phone doesn’t register that the land line is ringing although the home base unit is ringing through  the Vonage line.  If I call I phone to I phone, my cell phone screen registers that the other phone is ringing…frustrated…and ideas