Some of your messages are green because those are text messages sent through SMS while others are blue because they have been sent through iMessage. If there is no internet connection to use it will fall back to SMS instead of iMessage.
Blue means you are tx'n someone with a iPhone. Green means you are tx'n other cell phones. Now that apple made it free to tx from one apple to another it comes up blue. Also if you notice in setting you can see now when the other iPhone user is tx'n back and when they read the message.
iMessage allows you to send unlimited text, photos, videos, locations, and contacts using Wi-Fi or 3G* from your iPhone, iPad, or iPod touch to other iOS 5 users. For more information on how to use iMessage, see the user guide for your iOS device. A valid Apple ID is required to use iMessage on iPad and iPod touch. A valid phone number or Apple ID is required to use iMessage on iPhone. Note: On iPhone, if iMessage is unavailable, the message may be sent as SMS or MMS, depending on content. Carrier messaging rates may apply. You can turn this on or off in iPhone at Settings > Messages > Send As SMS. Messages sent using iMessage will appear in a light blue bubble, while messages sent using SMS or MMS will appear in a green bubble.
Basically, if your data is turned off and you are not in a wifi area, your messages will be delivered green...regular text message. You need to have an internet connection to take advantage of the imessage function.... blue messages.
blue means iMessages was used meaning its free unlimited messages because both parties are iPhone users and you both are 'unlimited data' or using wi-fi... by green means regular paid Text Message was used since the other end is Not Unli data or not in wi-fi zone or simply is not an iPhone user... be thankful if all your SMS are blue that means you'll never be charged since its unlimited free text offered to all iPhone users.
Hi, if you go into settings, click on the messages icon, then ensure iMessage is in the on position. This then ensures that if you are sending a text to someone who has enabled iMessages, it will be sent as an Imessage. This is for iPhone 5, but would think its the same for iPhone 4 and 4s as well
The thing you need to know is that when you accidentally delete a contact or group of contacts from iPhone, or lose or break your iPhone, this doesn't mean that your contacts are gone for ever. In fact, iTunes can automatically back up your iPhone contacts and update it every time you sync it. So you really get a big chance to recover contacts from iPhone backup. Recover iPhone sms http://www.istonsoft.com/iphone/recover-deleted-iphone-text-messages.html