My camera didn't come with a USB cable. Is it okay to use my phone USB cable or I have to buy a Nikon's cable?

The photos transferred without a problem using my phone USB cable.

Is it fine to use a cable that isn't from Nikon's?

Of course. One of the biggest scams in today's world is exorbitantly priced mini and micro USB cables.

Oh yeah. As long as it fits they're all the same. Just copper wires wrapped in plastic.

If it works.sure. Why not. As long as it doesn't get hot there's no cause for alarm

Some micro-USB connectors are better than others and sometimes a particular cable makes an unreliable connection with a particular device. If it works, it's OK. If you get data drop-outs, use a different one.

The newer cameras don't really come with USB cables, so you have to either transfer images by using SD card reader or purchase a cable. If the cable is physically compatible, yes you may use it. So, yes, you can use your phone cable on the camera.

If the USB ends fit, then it can be used on anything that uses a USB cable.

The situating is that you do NOT need a USB cable.

The workflow is to remove the memory card from the camera and insert it into a card reader. This copies files much faster that there's a much reduced chance that the connection between the camera and computer will inadvertently lose connection.

Using your computer skills, you copy all the image files on the memory card to a new file folder you have named for the subject/location and date so you can find your photos years later.

Once all the images are safely on the computer, remove the card from the reader, and insert it into the camera

Using the format feature on the camera, format the card so it is ready for your next photo adventure.

Do this routinely and you will NOT encounter some of the problems associated with attempting to use a USB cord to connect the camera to the computer or using the delete button to get rid of unwanted images. This bad habit can lead to corrupted image files or worse a corrupted memory card. Forget that your camera has a delete button

Any cable that fits will do.

You can buy a memory card reader for under $10. That makes it much more easy and faster to do.

If the plugs are the same, then there's no problem. However get a $15 external USB3.0 card reader will allow you to download photos 10X faster and with none of the connectivity problems that come with downloading directly from the camera.