what happens to text messages when there is no signal?

so with the majority of us facing this issue of bars dropping and whatnot, i had a question. what happens when i have no service/searching/0 bars and during that exact moment, someone sends me a text/picture message? will i just not receive it? will i receive it later once i regain signal? are the chances of receiving it lower? texting is what i care about the most, so the answer to this question will have a lot do with whether or not i keep the phone. also, when i am driving, i tend to put the phone between my legs near my crotch area (laugh all you want, but it's comfortable and convenient). i've noticed with the iPhone 4 that i always lose a few bars when doing that, because as soon as i pull it out, the bars go back up. a lot of times i have 0-1 bar when its under there but upon pulling out, it goes up to 4-5. so if i receive a text while its in that area, what will happen? if i receive a call, what will happen? will i not get them? will the call go straight to voicemail for the other person? thank you in advance.