HT4623 Since my update on my 5s I cannot receive messages from other iPhones. They all have to be sent by text. Why?

Question

Since my 7.1 update I do not receive messages unless they are sent as text.

Answer 1

iOS: Troubleshooting Messages
Symptoms
Learn how to resolve issues with the Messages app on your iPhone, iPad, or iPod touch. You'll learn what you need to send messages using SMS, MMS, and iMessage as well as how to resolve issues with each method.
Resolution
Before you start troubleshooting, learn the difference between SMS, MMS, and iMessage. The first step to resolving an issue with iMessage is to update your iOS software and your carrier settings to the latest versions. If iMessage still has an issue, follow the steps below for your issue.
If you can't activate iMessage with your phone number or Apple ID
See how to troubleshoot iMessage activation. If you're using a China Telecom or au (KDDI) iPhone, you can activate iMessage only on your home network. While traveling internationally, you can't activate iMessage.
If you can't send and receive iMessages
You will need these to send and receive iMessages:
An iPhone, iPad, or iPod touch
iOS 5.0 or later
A cellular data connection or a Wi-Fi connection
A phone number or Apple ID registered with iMessage in Settings > Messages
To resolve issues with sending and receiving iMessages, follow these steps
Check iMessage system status for current service issues.
Go to Settings > Messages > Send & Receive and make sure that you registered iMessage with your phone number or Apple ID and that you selected iMessage for use. If the phone number or Apple ID isn't available for use, troubleshoot iMessage registration.
Open Safari and navigate to www.apple.com to verify data connectivity. If a data connection isn't available, troubleshoot cellular data or a Wi-Fi connection.
iMessage over cellular data might not be available while you're on a call. Only 3G and faster GSM networks support simultaneous data and voice calls. Learn which network your phone supports. If your network doesn't support simultaneous data and voice calls, go to Settings > Wi-Fi and turn Wi-Fi on to use iMessage while you're on a call.
Restart your device.
Tap Settings > General > Reset > Reset Network Settings on your iPhone.
If you still can't send or receive an iMessage, follow these steps
Make sure that the contact trying to message you isn't blocked in Settings > Messages > Blocked.
Make sure that the contact you're trying to send a message to is registered with iMessage.
If the issue occurs with a specific contact or contacts, back up or forward important messages and delete your current messaging threads with the contact. Create a new message to the contact and try again.
If the issue occurs with a specific contact or contacts, delete and recreate the contact in the Contacts app. Create a new message to the newly created contact and try again.
Back up and restore your device as new.
If you aren't receiving iMessages across all iOS devices
Go to Settings > Messages > Send & Receive on each iOS device and make sure that you signed in with your Apple ID. You must use the same Apple ID on each device.
Go to Settings > Messages > Send & Receive > You Can Be Reached By iMessage At and make sure that you selected each phone number and email address you want to use with iMessage.
If you linked a phone number to your Apple ID with iMessage and the phone number hasn't appeared, followthese steps.
Sign out of your Apple ID in Settings > Messages > Send & Receive and Settings > FaceTime on all devices.
If you're linking a phone number to an Apple ID, sign in to iMessage on your iPhone first. Then sign in to the rest of your device one by one with iMessage and FaceTime.
If your iMessages didn't transmit as SMS when iMessage was unavailable for use
Go to Settings > Messages > Send as SMS and turn on Send as SMS.
Select your phone number when Sending iMessages in Settings > Messages > Send & Receive > Start New Conversations From.
Make sure that you can send SMS with Settings > iMessage turned off.
Source: http://support.apple.com/kb/ts2755