I work with a team from Bangladore daily and they frequently interrupt. I don't know if it's a cultural difference but it seems that way. I know when someone begins to speak Ill hear "ACTUALLY..." or "SORRY BUT..." soon enough.

Two things work. First is if I start a sentence I finish it. If you start talking then stop, you implicitly give permission to someone else to interrupt you when they interject. Get over the awkwardness of two people talking at once. They now (mostly) let me finish my thoughts -- after I started doing this.

This one is sneaky, but I do it when someone is especially obnoxious. They'll interrupt (on a call) and Ill say "Hey (name), are you there? We can't hear you." They freak out and beseechingly yell into their mic like Sandra Bullock in Gravity and then Ill calmly say "oh there you are, as I was saying..." and complete my thoughts. It's a pattern interrupt. Not the most honorable method, but it works.

I find I interrupting people while they speak to be terribly rude. I judge people pretty harshly who do so, which is probably my own hang up. These two methods have worked for me.