Naturally, through our work on Mobile Researcher and Mobenzi, we’ve had a lot of technology decisions to make along the way. It goes without saying (although I’ll say it anyway) that I do not believe in a “one technology fits all approach”. SMS is obviously great for ad hoc, instant communication and a range of other communication-oriented tasks. But it falls down in a lot of other, more complex (and sometimes more valuable) scenarios.

Here are 5 reasons why:

1. Usability

Although people are familiar with how SMS works, they aren’t normally familiar with what your service is or how it works. I’ve seen loads of solutions which force users to format responses (commands, requests, etc) in cryptic ways so that a system can understand them and render the correct service (e.g. looking up information). This is one of the main reasons we’ve built Mobenzi in an attempt to improve the usability of SMS by adding real people to the mix.

2. Cost

Although SMS costs are probably coming down (I hope?), when one considers the transactional cost of an SMS, it’s a hellishly expensive way to conduct multiple interactions with people. Cost can even be a factor with reverse-billed services because SMS has a perceived cost which can act as a barrier to user participation.

3. Service portability

If you’re planning to use a short code, you can almost forget about using the same one worldwide. It’s often difficult, expensive, and/or impossible to register the same code in different countries. This again reduces the usability of the service (or at least increases the training you need to do in each country).

4. Connectivity

While SMS coverage is generally much better than data coverage, it’s still patchy in areas (even in very mature mobile markets like SA). Using a system which can’t work offline (rather than a smart client application) puts you at the mercy of coverage dynamics.

5. Building for the future

I don’t have anything more than anecdotes and my own experience to support this but as if you look at even the low end models being brought out these days, its a relatively small percentage that don’t have internet connectivity. If you’re going to base your service on SMS now, it seems somewhat sensible to have a medium term plan to migrate it to IP. And be prepared to expend significant resources in that process. Swapping an engine whilst in flight might not be impossible – but rather expensive I would postulate.

Trying to take sides or apply a “technology x is better than technology y” approach is futile and in my opinion a waste of time which could be better spent leveraging an appropriate technology to solve a problem.

I believe the biggest barrier to wide-spread adoption of IP-based mobile services is that operators and manufacturers are generally pretty poor at shipping “internet-ready” devices. Don’t even get me started on signing applications which are able to use protected handset APIs.  That’s a rant for another, longer blog post.

Bulk SMS usually involves integrating with an existing database of users (from a CRM system for example) and automating the process of sending information to these users. A simple example is when you log into internet banking, you can elect to receive an SMS which contains your one time pin (OTP).

2-way SMS allows SMS’s to be sent to end users and for those users to respond to these messages. The response is then processed by the business application and some automated action taken.

Premium rate SMS is also 2-way in nature but allows for rates other than standard SMS rates to be levied. A multitude of billing options exist, including rate bands (where a set fee is charged for a number) and variable billing (where billing is based on the requested service or content). In a non-subscription type service, when a user sends an SMS to a premium rated number, funds are deducted from their cellphone account. In a subscription type service, funds are deducted periodically or on some stated basis. The network operator takes a share of the revenue and the remainder is passed on to the application owner or service provider.

What are custom SMS solutions good for?

• Reasonably simple interactions: exchange of information (predominantly text).
• Capturing larger (relatively) quantities of textual data.
• Simple “conversational” interactions – where the state of the interaction must be maintained or where the context is important.
• Revenue collection (via premium rated SMS).
• Textual information dissemination.
• Communicating with a large number of users, quickly and reliably.

What are custom SMS solutions not good for?

• Capturing structured, formatted information or data which must be validated in some way.
• Multiple, extended or continuous interactions (due to cost).
• Rich media (video, images, music, etc).
• Client-side processing (i.e. performing some custom action on the recipient’s device).

What is the extent of device support?

• Almost every mobile device worth considering (mobile phone, GSM-enabled PDA, pager, etc) supports SMS.
• It is by far the most widely supported mobile technology after voice.

Example application

Qpid is a premium rated SMS service, developed by Clyral which allows users to send anonymous secret admirer messages to one another in a safe way. The system tracks who “fancies” who and interacts contextually with each user (conversational). All interactions are text based.

This post forms part of a series on a comparison of mobile technologies.

Continue to Part 2 – WAP or mobile web.