SMS is a great way to push small amounts of text to mobile users. But what happens when your application needs to send more than 140 characters of information? Most modern phones, including Apple’s iPhone, support the ability to launch the mobile web browser using the URL embedded in the SMS message. Your application can create a short URL that points to the content you need to send and send the URL in the body of the SMS instead of the content itself. The user experience varies from phone to phone. On the iPhone, the user simply touches the link; on other phones, there is usually a menu option that will activate the url.

sms_url.jpg The URL is subject to the same size limits as any other SMS message. Keeping the URL as short as possible is key, allowing you to send descriptive text along with the message to give the user an idea as to what they will be viewing when they click the link. URL shortening services like tinyurl will keep your URL to around 25 characters. Twitter users are no doubt familiar with this idea, whether they send Tweets from their phone or not.

The web page that the URL points to needs to detect the capabilities of the mobile device and return the appropriate markup. In the case of the iPhone, a full HTML page can be returned, but for many phones, the content needs to be limited to the XHTML mobile profile, or as a worst case with the oldest of phones, WML might be the only supported markup. Device capability databases like WURFL will allow you to look at the user-agent of the devices and return the appropriate markup.

Make sure that your users actually want to receive the SMS before you send it. Most users have to pay for each SMS message, so filling up their phone with messages without their permission is not a good idea. Allow your users to opt-in to receiving SMS messages and allow them to place a maximum cap on the number of messages they can get per day or month. Also include a verification system that ensures that your user actually controls the phone number they give you. This can be as simple as sending an SMS message with a PIN number that they then feed back into your signup form. Lastly, include disclaimer text that lets the user know that standard text messaging rates apply to any messages you send them. Adding these safeguards will help to ensure that your users only receive the messages they want.

Adding SMS notification with embedded URLs has many advantages: you can reach your users wherever they are, provide links to detailed rich content, increase awareness of your mobile web offering, and drive additional traffic deep into your mobile web site. If your application already works on mobile devices and you already have the infrastructure in-place to send email or SMS alerts, then sending URLs in SMS messages is a simple addition that can add significant value to your users. A great example for this is the airline industry. Instead of just sending a user an SMS with their gate information and arrival and departure time, they could also send a link to a convenient, mobile optimized “My Flight” page that would include other essential details such as seat assignment, arrival time, airline phone number, first class update options, and airport map.