Anyone who knows me will tell you how much I love my gadgets. Of all the things my smartphones can do, I use them as communication devices first and foremost. Whether it's an old-fashioned phone call, conference call, email, texting, or an instant messenger client, I like to keep in touch with my family and friends.
Whether you are using your Palm OS Treo or Centro, or you have a shiny new Windows Mobile-based Treo Pro, there is definitely a hierarchy of communication methods. This hierarchy is predicated upon the required speed in communication and response time. Once upon a time, "snail mail", or the postal service, was the way we communicated, and now we can communicate at the speed of the electron via email.
With respect to response time, email carries the lowest expectation. When we send someone an email, it is usually with the expectation that we may have a response in a matter of hours or even days. If we require more rapid response, then a text message is a great way to communicate. Sending a text message, or SMS, just requires the mobile phone number of the receiver. Depending on the bit size of the characters (letters and numbers) sent, the maximum length of a text message is 160 characters, so the messages are intended to be short and concise, often filled with abbreviation and slang, to send the most information using the least amount of characters. I'm sure my daughter knows far more about texting than I do (she texts in the thousands of messages per month - yikes), but when texting, the response time becomes more immediate than one might expect with email. When you text, you can usually expect an answer within minutes or seconds if the other party is available.
Instant messaging clients (IM) are very popular on mobile devices now. There are numerous third-party chat clients, usually able to handle multiple services, like Yahoo, MSN, AIM/AOL, Jabber, ICQ, etc. Like email and SMS, using an IM client requires some kind of data plan (unlimited plans being highly recommended). IM chatting is even more immediate than texting - you are chatting only if the other party or parties are using the chat client at the same time, so communication is practically instant. Responses are expected within seconds rather than minutes or hours.
Finally, before we get carried away with all of this technology (and start texting people in the same room, like my daughter does, rather than speak directly), there is the old-fashioned phone call. These days, it seems like people are more concerned with what data plan they have and how many text messages they are allowed rather than how many minutes are available for actual phone calls. All of these methods are great and serve a purpose - email is a great way to document an interchange and fantastic for attaching and sending documents, pictures, and other files to the receiver; texting is great if you need to reach someone in a meeting, send an address or phone number quickly, or just remind someone you are thinking about them - but ultimately, the phone call is the most personal and direct way to communicate.
If you are unfamiliar with some of these methods - like IM, for instance - give it a try. Most likely, you will find a method or service that you are more comfortable with than others and may stick with it - some prefer texting and never use an IM client, for instance - but just remember, the people that you care about and who care about you will always appreciate the sound of your voice.