You sure can. If you’re located in your home 'footprint' and place an international call, then the call will be billed at the UScellular per minute rate for international toll, plus airtime and applicable charges and taxes.
If you are roaming and place an international call with another carrier, you will have access to the countries available through that carrier. The call will be rated according to the International toll rates charged by that carrier, plus airtime and applicable roaming charges and taxes.