It seems that Verizon Wireless has been quietly shutting down the SMS delivery confirmations service for their customers in order to "save network traffic".
According to DSL Reports, Verizon Wireless has been quietly ending their SMS delivery confirmations. You know those quick icon changes (letter D or a green checkmark) that occur when your text message has been delivered to your recipient; well, they’re suddenly not working anymore. Discontinuation of the service reportedly started on September 9th on a regional basis and all regions should see the service gone by the end September. According to the word on the forums, the service was stopped in order to reduce network traffic.
I think this is a bit over the top. They should change it so customers can opt in/out for this service, and not ending it.
Do you miss the SMS delivery confirmations?