When Erica Sadun of The Unofficial Apple Weblog contacted us a couple of weeks ago because she wanted to write about RF.com, we were quite honored.

From the moment Eric Chamberlain and I got our hands on the initial production models of the iPhone and we got to working on RF.com, we’d been following Sadun’s TUAW columns on the iPhone closely. As seen from our perch, Sadun had as much to do with Apple’s decision to open up the iPhone to outside developers as anyone; her useful native applets that worked only on jail-broken iPhones must’ve certainly opened some eyes and minds in Cupertino — as it did ours.

These days, we’re busy testing iPhone 2.0, which prevents us from jailbreaking our phonesand running Sadun’s apps. Particularly missed is her simple but effective voice recorder application, which allows recording and keeping audio “notes” on the iPhone when writing is inconvenient (like when stuck for hours in Bay Area traffic or pushing a three-year-old on the park swing). Hopefully, when iPhone firmware 2.0 is released, we’ll be able to easily install Sadun’s little gems right from the Iphone App Store.

While working on her TUAW column, Sadun ran into problems with RF.com’s registration system. Over the past couple of months, the focus of our development attention has been on the feature set the RF dialer offers: Skype calling, GoogleTalk calling, SIP URI dialing, compatibility with Asterisk and other office PBX systems. We knew there were circumstances where registering with the RF.com server was dicey, but we chose to address those later.

Sadun wrote about RF.com, and she was quite nice — nicer than she might have been, anyway. She talked positively about what RF.com offers, and made it clear that, as a Beta program, there are still issues pending. She could have rightfully criticized us for the finicky, overly intrusive, registration system, but chose not to.

Still, Sadun’s registration experience, which she described to us when we spoke, got us to revamp the registration system from the ground up. And now, we think, we got it right.

The problem had been that the registration process relied too much on ever-changing database records, session variables, constant page loads and back-and-forth communications between the iPhone and our server. Unlike the RF Dialer itself, a self-contained “Web 2.0″ application that runs relatively glitch-free, the RF.com registration process was decidedly a “Web 1.0″ offering. We thought we made it simple. And simple it was — as long as everything went right.

But if any small went astray (say, a blip in network connectivity) or the user would do something perfectly normal but unforeseen by us (like pressing the back button at a specific point in the process), registration would fail. Worse, in a few circumstances, registrations lived in a partially finished state in our database, requiring manual record-level intervention so the iPhone user could try again.

Now the whole process has been significantly trimmed down, and relies much less on constant back-and-forth data communication between you iPhone and our servers.

The whole registration process now consists of three short text entry fields, a four-digit keypad entry, two simple pull-down menus, six button/text clicks, and only a single communication between iPhone and RF.com server. On a typical Edge network connection, registration should take about 60 seconds (less for those with nimbler thumbs). We think we’ve captured all potential hick-ups, and now present relatively seamless recovery when the unforeseen gets in the way.

Now we can’t wait for Erica Sadun — and anyone else who tried to register with RF.com and gave up in exasperation — to try again. And if you do find something we may have overlooked, let us know. This time we’ll fix it fast.