Messages problem: iPhone 4S with iOS 6.1.3, iPad 3, & MacBookPro 10.8.3

Messages I send to some contacts and some contacts send me are coming to MacBookPro and iPad 3 but recently not to iPhone 4S. I have tried changing the settings and have used the information and consulted the images of the various menus. More and more contacts' messages are not sending/receiving between our phones. Some of my contacts have iPhones and the same carrier, Verizon, others have other phones and carriers. All of use could send/receive messages from each other previously.

The phone number is checked and grayed out on my iPhone when I look at the settings, as mentioned in the instructions regarding messages. What can be done to assure that all messages contacts and I send to each other are being received and can be viewed on our phones?

Thanks!