Entering a house with a mobile or bell hanging on the door

The Rabbi wrote to me that one should remove before Shabbos a bell or mobile connected to the door that makes a pleasant sound, or ensure that they do not make a sound on Shabbos. The thing is, in our area, this is a very accepted custom, and many times, I want to enter a friend's house, or leave it, and there is a bell or mobile hanging on the door. Is it forbidden for me to open or close the door on Shabbos in this case? I emphasize that nothing is electric, and the question that I’m asking is whether it is permissible to open the door on Shabbos.

Post factum, it is permissible, and you are not required to stay outside the house, provided that your intention is only to enter the house and not to make the contraption chime. But whatever can be arranged before Shabbat, has to be arrange. And if you can make your friends aware of this problem before Shabbos, you should do that.

Mishnah Berurah (Chapter 338, subparagraph 6).