The 463 area code entered service on March 15, 2016, as an overlay of the 317 area code that was already assigned to the Indianapolis area. More than two years later, Sprint still doesn’t offer 463 phone numbers.
See: https://en.wikipedia.org/wiki/Area_codes_317_and_463
The Indiana Regulatory Commission announced that area code 463 would be added in 2016 as an overlay. The new area code, which coincidentally also spells out IND on a standard telephone keypad. 463 entered service on March 15, 2016. On that date, a permissive dialing period began during which both seven- and ten-digit calls would be able to complete. Ten-digit dialing was originally to become mandatory in the Indianapolis area on September 15, 2016. However, on August 31, in response to an appeal from security alarm companies, the deadline was extended to October 15, 2016. Indianapolis had been one of the few major cities where seven-digit dialing was still possible.