VOIP and Taxes

It looks like VOIP traffic to PSTN lines might very well be taxed in the near future. One thing that this does is encourage institutions with their own PBX's to keep as much traffic as possible from hitting the PSTN by routing eligible traffic over private lines. One interesting method is to tie all participating PBX's together via the internet using globally unique "tie-line" numbers.

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ISN provides an easy way for campuses, enterprises, and ASPs to acquire globally-unique subscriber numbers to support new communications services. ISNs are free, fast, and forever yours; they may be used to support SIP, XMPP, H.323 or other communications; and, they provide a domain-based, "Internet-style" number that looks more like an email address than a traditional E.164 telephone number.

An ISN is formed by joining a domain-local subscriber number to an ITAD (Internet Telephony Administrative Domain) number, using an asterisk as the delimiter. For example, subscriber 1234 in ITAD 256 would have ISN: 1234*256.

Think of an ISN as an Internet-style phone number, where the asterisk is analogous to the @ sign in an email address.

Internet Telephony Administrative Domains (ITADs) were defined in Telephony Routing over IP (TRIP) [RFC 3219]. But, since TRIP never gained much traction, ITADs didn't either. ISN gives ITADs new life.