said by drivel:If everyone who had a gmail address could be called using a SIP call, it would quickly kill off the PSTN. i.e. gmail would be a replacement for enum.
While I believe eNum may be have less DIDs then Gmail addresses, DIDs for sure are a lot more than Gmail accounts. Let alone Google decided not to allow SIP connect long time ago. Now, Google does not even want third party to utilize their Google Voice. Users must use Google interface to communicate, a lot of people simply will not go for this.