Have a new 3gs and messages to some of my contacts are not going through and instead of blue the color is green
Thanks for your question. My name is Rofel and I will assist you with your concern.
First, toggle your phone into airplane mode and back, this resets network settings. Then try to send an SMS message.
Please let me know if this helps. Thanks
If the solution above did not work please follow the steps below.
When you tap on the new message button and you'll see the standard message composer with a Green SEND key. When you choose a recipient you'll notice a small loading icon right next to the name. If the person you are texting has the iMessage service, your SEND key will turn Blue and the top bar will say New iMessage instead of New Message.
If you just want to send SMS messages you need to turn off the iMessage settings on your phone.
Go to Settings->Messages and turn it OFF
Try to send an SMS and check if this fix the issue that you're experiencing.
If I were able to assist you with your concern please click on the Green Accept Answer button below my first response so that i get credit on helping you.