My iPhone 5 won't let me text certain people?

Alright, so on thursday night all of a sudden my text message wouldn't go through to this certain person. I tried resending it, and each time it would show the text message bar (right under the contact's name) saying "sending… " but once the sending progress bar reaches roughly 3/4th's finished, it'll just stop and the text message will put up an exclamation point (meaning that the message was not sent). I looked into it, and at first thought she blocked me, despite her saying she can't text me either. I assumed she'd blocked me and just left it at that and continued on. When I was texting another contact, the same things happened. I asked her and she too said that it wouldn't let her text me back. While researching this problem, I found out that maybe the IOS 6 software update that came out a few days ago was causing this problem as others have been experiencing it as well. Currently, it won't let me text those two people, but every one else works fine. I have resorted to Facebook messaging them, but I'd prefer texting since it's faster! Any advice or information is welcome. Thanks!

PS: I already edited their contact information, putting a "1" in front of the area code for long distance and that did not work.

How to free up storage on an iPhone 4s (8GB)?

Apparently, I only have 1.4GB left. I deleted Photo Library off my camera, but it still says photos are taking up the bulk of my storage. I only have 197 photos and 27 videos! One of them is 12min long, so maybe that's it? But I only have about 20 apps (the one that takes up the most is Facebook). I deleted mail I don't need (I only have about 5 in 1 out of my 3 accounts) including trash and sent. I got rid of two out of the four TV episodes off my phone. I went down from 303 photos 197 and still!

How do I do it?

Added (1). I only have 495 songs.

Is getting an iPhone worth it?

I currently have a Windows Phone, but a lot of people say to get an iPhone as there more popular with apps. Is it worth getting an iPhone?

Otter box Defender vs Commuter?

I have an iPhone four in a defender case and I love it but the silicone is ripping and streatched after all this time the commuter has a hard outside but does it protect as well?

How to unlock iPhone 4 for tmobile carrier?

Like unlock the SIM card so I can use tmobile my mom went to tmobile but they said I have to do it by mail if you did this how did you do it or is there a place I can go to

Cheap alarm clocks for iphone 5?

I've been looking everywhere for one and just can find any below $40… D:

So if you know of any and could please give me the link i would be very very very very happy and give you 10 points.

Added (1). What i mean is like a clock radio that is not an app
it is an actual thing

How to stream FROM my iPhone to my computer?

In TyPlaysGames' videos he says he's streaming from his iPad to his computer to make Minecraft Pocket Edition videos. I was just wondering if there was any (free) way that I can do this from my iPhone 5?