I think a lot about design – mostly in how it affects me or affects others. Sometimes that’s an emotional effect. Other times there are material consequences to design choices – either negative or positive. I’ve written about some of these in my former blog.

Lately, I’ve been encountering more situations where a lot of design or optimization has been applied to something which is in fact a component of a system. Yet the system design and optimization was completely neglected.

Of course it is possible that optimizing your component will improve overall system performance. But the opposite is also possible, and even likely. Fix a traffic intersection here, create a worse problem over there and in fact hurt overall performance.

One situation I experienced recently happened with switching my family plan from AT&T to T-Mobile. I experienced these positive design elements:

• Great plan designed to reward me for holding onto my phones for longer
• Lowered my monthly bill significantly
• Gave me a great international experience traveling to Europe

But then poor reception at my house ruined the entire experience for me. T-Mobile has solved the poor reception problem for some people by offering WiFi calling – a feature that lets you make and receive calls using your smart phone over WiFi when a cellular connection is not available or is too weak. However, T-Mobile cannot modify the phone app in the iPhone. Only Apple can do that. So as of yet, WiFi calling is not supported with the iPhone.

To be fair to T-Mobile, I’m sure they *want* to solve the reception problem for me. But both paths open to them are tough nuts to crack. It may not be economically viable to stand up a tower in the hilly terrain with low population density near my house. And I’m sure Apple does what it wants, not what a late-to-the-party carrier wants them to do. Nevertheless all of the design and optimization done to the other parts of the system failed to deliver the overall experience necessary to keep me as a customer. After a month of suffering through missed calls at home, I switched back to AT&T.

AT&T actually doesn’t have good coverage at our house either – at least not without that MicroCell sitting in the study. I used to think a MicroCell was a less elegant solution than WiFi calling. But it works. And when it comes to using the cell phone, the most beautifully designed phone won’t do you any good if you can’t take calls with it.

Update (Dec 2017): Since I wrote this post, T-Mobile came out with WiFi calling for iPhone. And having used the WiFi calling feature a lot since it became available on both carriers, I’ve realized it has saved me from many ‘poor reception’ areas besides just my home. I’m thankful for the people that did not neglect the design of the overall system in this case.

What system design challenges have you encountered recently?