Really, the 2500 ms to decode the caller ID is quick, if you understand what's really happening. Your phone company sends CallerID between the first and second ring. This is because in the days when CallerID was first offered, phone circuits weren't as "clean" as they are now, so if an external CallerID device (which is what many subscribers used initially) was used, it would only "listen" for Caller ID in the first second or so after the first ring was received. If they had left it monitoring the line constantly, it might have accidentally decoded line noise, FAX tones, dial-up modem tones, etc, and it might have displayed wrong or nonsense numbers from time to time.
The Obi can't decode CallerID any faster than the phone company sends it, so it has to wait until it receives the Caller ID data IF you want that data. I suppose that it could directly connect the phone to the line via a relay when ringing occurs, but then you'd lose any possible call processing benefits of the OBi (such as the ability to forward calls from certain callers but not others).
The only thing I might wonder is if they could start pre-ringing the phone before the CallerID is fully decoded. I would think that would be a programmer's nightmare, but then I'm not a programmer. The idea would be that if the line is ringing and you are using a conventional ring cycle of two seconds on, four seconds off on the phone, and you have the delay set for 2500 ms, then in theory you could start ringing the phone one second after the line begins ringing, because you know that you only need 500 ms after the line stops ringing to receive the caller ID and maybe another 500 ms to make any decisions on call routing and prepare the caller ID to send to the phone after then end of the first ring on the phone. But the downside would be that you'd have to take into consideration the possibility that the phone might be using an initial ring of less than two seconds, and then if it turns out that the call is being forwarded or otherwise disposed of in some manner that doesn't involve sending it to the phone, the phone would have already rang a half-ring for no reason, and a lot of people would find that highly irritating.
