Yes. Most VoIP providers offer free calling between your offices as long as they are on the same system and calls within their network. So there is definitely money saving there. But, it’s much cheaper to make any type of phone calls using VoIP vs. traditional telephony. This is true for IP to IP, IP to PTSN, international, long distance, etc.
So in the end, switching to a VoIP service will save you money on your phone bill no matter whom you are calling.
Stay tuned for VoIP Myth #5 – You’ll lose existing numbers