Mobile Application Gap

[sd]: http://sprintdevelopers.com
[tf]: http://www.teleflip.com
[sp]: http://sprintpcs.com

Like every other wireless carrier, [Sprint PCS][sp] offers an e-mail to SMS gateway. You can send messages to Sprint phones by addressing an e-mail like 8005551212@messaging.sprintpcs.com. Sprint will get the e-mail, pick out the first 120 characters of the message and send them as an SMS to the corresponding phone number. To send a message to a Verizon subscriber, you need a different gateway, 8005551212@vtext.com. So what if you don’t know which carrier the recipient uses? Remember, the Number Portability system means everybody can change their carrier without changing their number. That creates a maintenance nightmare for you.

[Teleflip][tf] tries to solve the problem by acting as an intermediary. Just send your message to 8005551212@teleflip.com and [Teleflip][tf] will figure out which carrier goes with that phone number and forward your message to the appropriate gateway.

I bring all this up because SendNote allows you to send text messages to other carriers by using e-mail. If you want to simplify things a bit, you could just put “@teleflip.com” on the end of all your phone numbers rather than trying to divine the appropriate gateway on your own. It sounds simple enough, but there are some important things to keep in mind.

1. Privacy - By using an intermediary, you are giving Teleflip access to all the content you send. They could read every message, archive them, keep logs on who you write to and how often.
2. Spam - Teleflip is free which makes me immediately suspicious that advertising is soon to follow. How can they possibly operate this service when there is no revenue in it? I would not be surprised if Teleflip one day decided to use their massive database of phone numbers to send advertisements based on the subjects discussed in your text messages. It could be much like Google’s gmail system that targets ads based on your e-mail content.

Teleflip’s convenience might make up for these concerns. That’s up to you to decide. I will point out that my own website also provides a messaging gateway through an HTML and WML form. I don’t charge any money for it and I’m not building a database. I run some ads on [SprintDevelopers][sd] that pay for everything. Well, it pays for everything when visitors actually click on the ads, but so far it’s breaking even. Lots of people use my service but it doesn’t amount to much bandwidth.

I originally designed SendNote to use Sprint’s resources directly. The program can submit messages directly to the form at messaging.sprintpcs.com. It can send e-mail directly through Sprint’s SMTP gateway. This ensures that SendNote will work even if ApGap goes belly-up. However, if you’ve been following along, you know that this approach is fraught with it’s own problems. Every time Sprint changes their text messaging form, SendNote breaks. Trying to parse the giant form response from Sprint is difficult for tiny J2ME devices. Keeping SMTP support in SendNote makes the program larger than it needs to be. I found that sending my messages through apgap.com works much faster and more reliably.

Yes, I realize that there is no real security when dealing with the Internet in general. All of your e-mail messages pass though countless SMTP relay servers everyday. You never know who is reading your messages. I have to say though, it’s just a bit different in this case. Normal e-mail has anonymity by its sheer bulk. With [Teleflip’s][tf] system, they know a lot more about the nature of your messages. Besides, you agree to their terms and conditions to use their service. It’s just not the same as the unknown e-mail routers scattered around the net.

Who out there is worried about these issues? I’m considering two things.

First, I’d like to offer a complete set of PHP scripts that would enable you to setup your own messaging gateway. It would come with a new SendNote client that would be much simpler than the current implementation. It would likely work faster than the existing program and provide you with a bit more privacy. Of course that would mean you’d have to setup your own server. I’d remove the option of sending directly through sprintpcs.com. I could keep a gateway going on ApGap for those who don’t care about the privacy.

Second, I’m thinking about an encrypted SMS service. Is there a demand for such a thing? I could create a J2ME MIDlet that used public key encryption to send messages to similar MIDlets. Such a system would ensure privacy but you could only send messages to people who also have the client software.