Google has offered its side of the story in an ongoing case with the Federal Communications Commission (FCC) over the blocking of phone numbers on its telephony service.
The company issued a response to the FCC explaining how the system works and why it blocks certain numbers on Google Voice.
While much of the letter dealt with FCC inquiries as to how Google Voice functions, Google also addressed reports that certain numbers had been blocked, possibly violating FCC rules.
Google explained that it had blocked around 100 numbers which it had believed to be connected to a sex chat billing scam which the company described in detail earlier this month.
Google claimed that the numbers were located in rural areas and were accounting for 1.1 per cent of total traffic but taking up more than a quarter of all operating expenses.
After investigating the matter, Google found that the calls were being directed to carriers in the rural areas that were charging a premium for connection and termination fees. In turn, Google said that it put filters in place to make the offending numbers inactive on the Voice service.
"Google Voice now maintains a restricted list only for those specific telephone numbers that match our data filters and appear to be associated with local carriers and associated businesses generating substantial in-bound traffic," the letter read.
"We utilise a look-up table which is checked on every outbound call to determine if the number being requested is inactive."
The response is the latest in an ongoing tussle between Google, AT&T and the FCC over the voice service. AT& T has accused Google of violating net neutrality rules by blocking the numbers, while Google has maintained that it is using a perfectly legal method which other carriers employ to stop billing scams.
Equinox's Dave Millett explores how phone, mobile and broadband could be affected by a no-deal Brexit
Dust storm on Titan only the third Solar System body where such storms have been observed
New technique could enable quantum computers to scale-up to millions of qubits
Systrom and Krieger taking time off "to explore our curiosity and creativity"