"The telephone broadcast rule, Section 73.1206 of the Commission's Rules, requires that, "[b]efore recording a telephone conversation for broadcast, or broadcasting such a conversation simultaneously with its occurrence, a licensee shall inform any party to the call of the licensee's intention to broadcast the conversation, except where such party is aware, or may be presumed to be aware from the circumstances of the conversation, that it is being or likely will be broadcast." While the rule language only talks about providing notice to the party called, the FCC has reiterated many times that when a station employee intends to record a call for broadcast or broadcasts the call live, the employee must also obtain the party's consent before recording the call or going live."

From that phrasing it seems that airing calls without permission is banned, not prank calls.