I just started doing the following and it has helped.
A lot of my parents are avid text messager senders. I'm not, but I learned that I can E-Mail my messages right to their cell phones. When I do this I usally get immediate responses and even when I don't I know they get the message because I know how much they use their phones. You get their cell numbers and providers from then and then add the tel numbers to following.
ATT or Cingular - number@cingularme.com,
number@mobile.mycingular.com,
number@txt.att.com
T-Mobile - number@tmomail.com(Update: If it doesnt work, tr