There are providers out there that have free VOIP numbers. You sign up for one under a phoney name, buy a POTS adapter and register it to the free phone number. You can then use the number as is, or get a google voice redirect number. At any rate, you give out the number and people call in.
A proxy is a web service that hides your geolocation by using some other IP or range of IP's. This is a service you pay for in most cases to browse the web anonymously. You can also use it for other things too, like streaming, chat, ect.
+-RH