If your laptop has a built in mic, you should be fine. I do this type of shop all the time with different companies and just talk outloud like my computer speaker phone. My husband does also and he prefers to use a pair of gaming headphones that have a built in mic. My biggest problem is the dogs barking or doorbell ringing or other ambient noises when on speakerphone but to me that makes my call seem more legit!
THere is a way in Windows to test your Mic in advance, and see if it is working, picking up your voice. There are also a few websites that let you do this, test your camera and/or your mic for use in other situations.