I once heard R. Feivel Cohen comment on the common message on answering machines "I'll call you back as soon as possible." Are you really going to call that person back as soon as possible? Isn't it likely that you might make a few detours and perhaps delay a little before returning the phone call? R. Cohen stated that he personally does not say on his answering machine that he will call the person back immediately.
When I mentioned this to R. Daniel Z. Feldman, he wasn't too sure that this analysis is correct (note that this was just in conversation and he might have changed his mind after thinking about this further). After all, does anyone take the statement in that context literally? Does anyone expect you, after you hear the message, to immediately drop everything and return the call as soon as physically possible? No. If so, there is no deception and no need to avoid the conventional phrasing.
While he made a good point, I've still tried to maintain R. Cohen's stringency simply because I prefer to be as precise as possible.
I recently saw that R. Aaron Levine, whose book Moral Issues of the Marketplace in Jewish Law will be published shortly by Yashar Books, discussed this in an earlier book of his, Case Studies in Jewish Business Ethics (pp. 321-327). R. Levine's case is whether someone who states in a message that he will return phone calls is obligated to return the call of everyone who left a message. He writes (p. 323):
The determinative factor is not Wolfgang's [the home owner's] intentions, but the understanding of those who are exposed to his recording. Undoubtedly, their opinions will differ. What counts is the opinion of the average or reasonable person in the group. If the average opinion among those exposed to the recording does not take Wolfgang's promise to call back to be directed to the caller at hand, but instead see it merely as a promise to someone whose call Wolfgang has invited, then Wolfgang's recording is not morally objectionable.See that section of the book for more details.