Took one phone out and now we have a “sometimes” static and can’t hear

Took one phone out and now we have a “sometimes” static and can’t hear

I have a Vtech 6629-3 With 4 lines. We also had a 2nd Vtech system with 2 lines. We were able to use both together. We now only have 3phones from the 6629 system in use and one from the other Vtech system in use.