1) "Sorry to interrupt your story about bathroom fittings in the 1980s, but it looks like a tree just came down outside my house. I'd better go investigate." Hang up.
2) "Sorry to interrupt your story about which private school to enrol your unborn child in, but I seem to have trapped my hand in a food blender and my chinchilla is perilously close to the 'on' switch". Hang up.
3) "Sorry to interrupt your story about the syrups of South America, but every time you call me, my heart sinks. I really don't find your life interesting, we seem to have nothing in common, you talk at me rather than to me and I would prefer it if we didn't talk anymore". They hang up.
It's not a perfect system, and I'd like to make it clear I accept no liability for any consequences arising from your use of these three very precise techniques. May your Wednesday evenings be fun and fruitful.