According to treocentral.com, some users of Sprint’s 700wx have had problems sending SMS text messages. In some instances, Treo users are not able to send SMS messages to recipients using other carriers or certain other Sprint phones. In other cases, Treo users may receive duplicate messages, particularly if the messages are longer than 140 characters.
According to the site, Sprint customer service is aware of the problem but has not yet provided a fix for it: “Palm and Sprint are aware that 700wx customers have been experiencing issues sending SMS messages within and outside the Sprint network. … We are working on an update which will be available via the web or over-the-air by the end of the year. In the meantime, Sprint customers may request credit for any charges incurred as a result of this error.”
Treocentral has a forum discussing the Treo SMS problem. And you can always contact Sprint customer service if you need specific help or want your account credited for the extra text messages.
UPDATE 11/21/2006: Palm has issued a patch for the Treo 700wx that fixes this problem; Treocentral has the details. Or click here to download the update from Palm.