Boult said:
Yeah because both use SIP which you can use existing phone number.
http://en.wikipedia.org/wiki/Session_Initiation_Protocol#SIP_network_elements
http://www.ojophone.com/buy/
http://www.ojoservices.com/help/
Now we knows that SnapVRS is NOT offering OjO for free AT ALL..
but the service offered by SnapVRS IS free but not the device itself.
But there seems to be details missing.
If you have an Ojo in the house, and a regular telephone line with a regular phone or TTY, how can your "existing" phone number be used? ENUM / DUNDi accounts for VOIP telephone services, but not for existing telecom services. I've never heard of VOIP services and regular analog service ringing at the same time, so unless it's an incredible engineering feat, something's up.
For example, if I have an Ojo and local phone service (like SBC) at 555-222-3333:
1) Someone calls me on TTY at 555-222-3333. I want to answer on the TTY, so I need my TTY to ring. But according to what I'm reading, if I have to pay for a Ojo service, my calls would be forwarded to the Ojo. None of my house phones will ring.
2) Someone calls me on the Ojo at 555-222-3333. I need my Ojo to ring. My TTY will never ring because I'm not paying for a VOIP service to my TTY.
3) Let's say this miracle of engineering works. Both my TTY and my Ojo ring. I pick up my Ojo. Now my 555-222-3333 line is supposedly "busy." However, the circuit through SBC to my TTY is free, because the Ojo service doesn't come from SBC. That would mean someone could call me on the same number again on the TTY while I'm on the Ojo. That would affect the Ojo service as ENUM is forwarding call still.
The same for if I answer on the TTY, now my line is taken up by the SBC circuit. Any additional calls should either be busy or if the Ojo service is so great, the Ojo should be able to receive calls because the ENUM translation occurs somewhere up the line. I don't know enough about that yet.
Anyway, I could be talking out of my ass, but that's the way I see it in a logical format.
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Edit: Reviewed the SnapVRS website closely. In their FAQ, they state you can use the telephone line for "voice only" calls on the PVP-1000. To make SnapVRS calls, you need to have a high speed internet connection. So, that means that dialing "711" is just having another directory server that has SnapVRS's centers as 711, not actually dialing 711. Confusing before, clear now.
They state nothing about the PVP-900 which states that audio calls can be made as well, but only has a ethernet connection. Confusing, but not addressed on SnapVRS's website.
SnapVRS states that you can travel and yet you can still keep the same phone number. This again, confirms there has to be some kind of directory server like the VP and i2eye then, except now, you're probably paying $15 a month for it. No thanks.
read carefully! 
Videophone device brand name motorola OjO & Server! Other provider WorldGate’s Ojo uses the broadband Internet infrastructure to transmit and receive video calls, they contract with motorola system's device!