PhoneBurner sets calling hours by default to 8am -9pm. Users are able to adjust this, but they should be aware that Per FTC regulations:
The TSR prohibits deceptive and abusive telemarketing acts and practices. It establishes standards of conduct for telemarketing calls:
Telemarketers can't call you before 8 a.m. or after 9 p.m.
Users are able to set call times outside of these hours, but it is their responsibility and they must be aware they may be held accountable for their calling actions.
The Phoneburner system will not allow it to be set specifically to 24 hours, but it can be set from 0030-2330.
Please be aware that certain states may have more restrictive time limitations.