What would cause a neighbor's phone to ring when I get an incoming call to my house?

We have cordless phones and lately have been noticing back ground noise when on the phone (landline). Also noticed a strange echo effect sometimes. Then today my husband called home from his cell and when I answered we could both hear someone else's answering machine picking up. We both hung up but my phone continued to say "in use" for several minutes presumably while the other person's answering machine finished going. Then my husband tried calling back and as I answered another person also answered so I told him to please hang up because he was somehow tied into our phone line. It was not a faint background level, he was loud and clear. Do you think this is a phone line problem or something to do with cordless phones? Our internet has also briefly gone out several times today & I wonder the problem is related.