Instruction: Generate an answer to the question by utilizing the information contained in the document.

Input:
Question: Can it work on the USB power, or is it only for charging?
Document: This product did not come with the charging bases, came with the USB charging units instead. Did come with PTT headphones, which I'd had known that before I ordered some for it but now we have a back up!
Very good radios. They are easy to operate. My family and I use them at the lake, while camping, etc.Charging is easy through the mini USB port, and they also use regular alkaline AA batteries, if needed.
First of all, there are a lot of good things about these radios, otherwise I wouldn't have bought them. The mini USB charging port allows me to charge it with my hand crank/solar charging emergency radio ... which means if I'm in the woods, I'll always have a comm life line and a flashlight with these things. I like the solid lanyard eye, because it is a very good place to attach it to my gear.
The mini-USB port allows you to purchase a cheap vehicle charging cable to charge them. I got two - one that plugs into a USB port and one that plugs into a vehicle cigarette lighter style port. Each was about $3. My sister had a similar Motorola radio that required batteries only and that caused problems when the batteries got depleted. I just plugged these radios in occasionally and they ran fine for the duration of the trip.
Good radios, sound a little canned until the speakers break in. Battery lasts a good while. Definitely prefer the USB charging these things have over the cradle chargers. I would have given 5 stars instead of 4, but I would say the 35 miles range is highly exaggerated. I have found them to have a fair amount of static at 2 miles in a fairly flat area without building obstructions.
These radios are a great deal. They work. I have just ordered my third set. If you are in the market for a bunch of these, the 3 pack isn't such a good deal. Of course the range is stated under perfect conditions... so what, they all are, get used to it! These radios still do perform. Better yet, they are weather "resistant" and rechargeable by USB - which is why I have included them in my BOB(s).
I was surprised how large the handsets were, but the big issue was that one of the handsets didn't work despite following the guidelines for charging.The intent was to have my kids and parents stay in contact while around the neighborhood, biking or camping. Even if it wasn't defective out of the box, the handsets were quite large (larger than I expected) which would make it too bulky for kids to carry around conveniently.
I call me kids to dinner using these. I feel confident that they are always within voice reach.Our use onboard the cruise ship encompassed over 9 decks and the entire length of the ship. Once again, there were no issues and the radios worked as hoped. They come with two charging cords, one splits so you can charge two radios at once. Charging time was not a factor as we charged them up over night while sleeping.I would say that these radios are well made and work as intended.
Good quality, good battery life, useful high power mode and the noise reduction feature. Worth it. But  like all other similar radios, you can't count it'll work 35 miles in city, not even 5 blocks.
Bought these for traveling between states with multiple vehicles. They work great and using them was way better than trying to dial a phone while driving our big trucks. The only down side was that the have less than 1 mile range even at full charge and using the high power button, that is the reason for dropping one star.
Answer: It can and does work on the USB power.  I leave it plugged in and turned on permanently as a wireless intercom from upstairs to downstairs.