Why are my imessages failing to send?

Question

Today I have been experiencing issues with iMessage.  Not sure if this is the proper place to post.  I have iMessage installed on both my iPhone (4s v. 7.0.4) and MacBook Pro running Mavericks.  First it appears the message I send has been delivered.  The the status changes to either an exclamation point on the MacBook with a popup option to cancel or send again or an exclamation point on the phone with "not delivered" below the message and an option (popup) to either Try Again, Send as Text Message or Cancel.  Try again generally repeats the process.  I was successful sending as texts a few times.  Currently one conversation from my MacBook has the failure message but the other party is receiving the messages on their phone.  The status page (http://www.apple.com/support/systemstatus/) indicates that everything is working as it should.  Don't know what the next step is.

Answer 1

Hi,
Where I live is abysmal coverage by several of the Phone Carriers i could use.
In most cases I don't get 3G.
Despite adverts on the TV for 4G the coverage tends to be restricted to really big cities.
They claim more
This means I can't iMessages on the service I do get when outside WiFI coverage.
So it may be the type of coverage you are getting from the Carrier.
Of course they could be looking at a coverage map to see if you are getting 3G or better when in fact you are not.
It says this under the Map in the link I posted.
This map is only a guide and not a guarantee of service availability in a particular location. As with all radio-based systems, service may be affected by a number of local factors, such as building materials, tree cover and weather conditions. You'll need a 4G phone, SIM and plan as well as 4G coverage to use 4G.
Why the map isn't perfect.
10:09 pm      Friday; April 4, 2014
​  iMac 2.5Ghz i5 2011 (Mavericks 10.9)
 G4/1GhzDual MDD (Leopard 10.5.8)
 MacBookPro 2Gb (Snow Leopard 10.6.8)
 Mac OS X (10.6.8),
 Couple of iPhones and an iPad