Historically, intelligence monitoring of communications providers was done extra-legally (by employees at the communications providers who either worked directly for or were compensated or politically-motivated agents of intelligence agencies). When it doesn't need to be used in court, there are a lot more options. Stuff as simple as an employee providing copies of the day's tapes.
Later, intelligence agencies got smart (particularly the Israelis) and ran cut-rate service providers for support services (VoIP termination, billing reconciliation, etc.), selling to existing consumer-facing providers, primarily for information.
Just because FBI is talking about this for law enforcement purposes (implying they don't have it now) doesn't mean they don't necessarily have various types of existing access for their dual role as a counterintelligence agency, or that other organizations (US and foreign) don't have access.