CyberSpatium, Thank you, that was the answer I was hoping for.
Meanwhile I managed to start Apache by disabling a number of services (incl. Skype), then I rebooted, then started Wamp. Then I started Skype, and it's running at the same time now!
Inspired by your reply, I checked the Skype options and found that the incoming port can be chosen, at least for incoming connections. (Tools>Option
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