To be upfront, my agency represents iotum and GrandCentral and I have spent a lot of time figuring out how they are different, and they are. Not only are they different, they are so complimentary that it's scary. Alec's post and his comment about Sitofono and iotum are spot on, and requires some additional commentary and in essence provided the genesis for this post.
First off, iotum's Relevance Engine is far deeper than simply "Find Me, Follow Me" and unified messaging, the territory which Grand Central is staking out and winning well in. All the "Find Me, Follow Me" solutions offer a binary "rules" based solution that is nothing really more than "on" or "off." They have their instruction sets, AKA "the rules" that can only be changed when the person changes the rules.
The difference here is iotum changes the game.
iotum is a game changing platform for making sure the right communication gets to you, at the right location, at the right time. This is not just for voice, but for any real time communications method. iotum does the thinking, and that thought process is different than the binary or rules based "send calls to voice mail" rules based technology that Grand Central or any of the "Find Me, Follow Me" services use.
Nowadays it is possible to have your calendar updated by a third party. In the iotum Relevance Engine world when that happens iotum will recognize the change in availability and handle things differently compared to how it would have when the calendar had nothing on it at that precise moment in time. When you go away from the keyboard or begin using a different device/phone iotum knows by presence what to do and again handles the calls differently. iotum does this because it draws upon the contextually relevant data to make it's decisions. That contextual data is within the calendar and from a person's presence status. It is after those two data points are taken into consideration that iotum's Relevance Engine then draws upon the rules the user has defined to make decisions in a manner far different than binary rules engines currently in use today. The end result. Only the calls that really need to be presented end up ringging through.
Now here's where GrandCentral comes in. Their platform automatically routes calls to the end points the user has defined. While today the calls are really only going to PSTN. PSTN replacement VoIP services (i.e. Vonage, CallVantage, TrueVoice, etc.) I suspect it won't be that far off before SIP endpoints and even Skype numbers become reachable, something already being done or in well developed lab experiments by two other clients, PhoneGnome and TalkPlus. The routing of calls by Grand Central then begins, after iotum has decided that the person is:
A. Available to receive the call
B. Open to talking to the calling party
C. Accessible by phone, mobile phone or soft phone/IM client
If the called party is not available, iotum tells GrandCentral to store the calling parties message in the unified voice mail box but what comes next is the sexy, game changing part and where the iotum/GrandCentral combination would really shine. The Relevance Engine then goes into action, determining when to notify the called party, how to notify them (IM, SMS, EMAIL, WAIT UNTIL FREE, etc.) What's more, if all members of a work team are on the combined iotum/GrandCentral system, iotum would know when to return the call, or plan the calls for you when both parties are available. That would immediately reduce telephone tag, but what's more it would also reduce drag on the networks for calls not being completed, and voice mails being left as part of telephone tag. In turn this reduces costs for network operators in a variety of ways.
To some extent this may sound like the recently Cisco acquired Orative, but Orative was geared only for the Enterprise, not disparate, ad-hoc free form networks, like social networks, social groups and families or even small businesses and organizations with people in different locales. As such, the blending of the iotum/Grand Central technologies means anyone using either a GrandCentral or iotum number (that is keyed to a SIP address) would have the basis of receiving relevant communications, at the relevant time, without unnecessary interruptions.
This would also be without the relevant costs. That's right. Costs.
FindMe/Follow me services cost money. In Europe where the calling party pays for the call to a mobile, the receiving party who uses a Find Me, Follow Me service then pays too, when the service is looking for them and when it completes the call or takes the message. This is exactly what happens each time Webley/CommuniKate, a 1.0 and very solid pre-cursor to GrandCentral. So between costs to the callers, the recipients and the cost on the networks for calls that only go to voice mail, there is also the cost of the time of tag itself. For consumers of bandwidth, this also will be meaningful too, especially those using mobile data where buckets of kilobytes are sold. With EVDO Rev A, UMTS and HSPDA all emerging, Voice traffic will move in a "Robin Hood" or Captain Bley market as we're already starting to see. The shifting of calls over the data side will eat up bytes, and the mobile operators are smart enough to see that and will price for that. Here again the iotum/GrandCentral combination works as their combined technologies far out class anything currently offered by any mobile operator anywhere.
Now add in Sitofono. The flat rate call set up concept is perfect for business users as Sitofono is paying for the call in both directions, but Sitofono combined with iotum and GrandCentral can become very personal too, as the troika becomes click to call, should this call reach me, how is the call handled, where does it go, how does it get there, and so forth is a far cry beyond being only the Voice 2.0 version of a toll free number.
Now to go to the next level. Sitofono, iotum and GrandCentral makes knowing a person's phone numbers irrelevant, because for the global number hopping, SIM swapping, SIP routed world you can change your number and not worry about having to tell the world as your services know where to locate you. Instead identity and presence begin to matter so once the system is in place, set up and running, the ability to be in total control of your inbound and outbound calls becomes much, much easier, by becoming more time and cost efficient. No one needs to know where you are, what phone number you're using. They just reach you. It's simple. It's easy and cheaper. While one number, one service may be good when you're in "one country" that concept breaks down to anyone who crosses any border.
In a nutshell, "Efficient Attention Management" for the always (need to be) on, stay connected crowd.
P.S. I could add in TalkPlus and this would be a foursome, but if I did that concept for now would be total 'foreplay' but someday soon, a reality, for all these Voice 2.0 services can play very nicely together.