Android - cdma-sms

GSM SMS defines six types (Protocol Data Unit (PDU) types) of SMS message:

• Deliver: a message sent from the service center (SC) to the phone.

• Submit: a message sent from the phone to the SC.

• Deliver report: sent from the phone to inform the SC of a failure in a Delivered message.

• Submit report: sent from the SC to inform the phone of a failure in a Submitted message.

• Status report: sent from the SC to inform the phone of the status of a message previously submitted by the phone.

• Command: sent from the phone to invoke an operation at the SC.

CDMA also defines six message types. Like GSM, it has Deliver and Submit types. The other types differ from GSM:

• Deliver: message sent to the phone

• Submit: message sent from the phone.

• Cancellation: from the phone to the Message Center (MC) to cancel a submitted message.

• User Acknowledgment: sent from a phone that has received a message to the submitter to inform it that the user has acknowledged the message.

• Delivery Acknowledgment: sent from the MC to inform the phone of the status of a submitted message.

• Read Acknowledgment Message: sent from a phone that has received a message to the submitter to inform it that the user has opened the message.

Application layer

A message can have a Protocol-Identifier field to specify a higher layer protocol being used. The standard does not define the operation of such protocols.

A message can have a Teleservice identifier to specify the application. The standard defines the operation of six teleservices.

The Wireless Messaging Teleservice (WMT) is for short text messaging between users. The Wireless Enhanced Messaging Teleservice (WEMT) extends this to include EMS elements such as pictures.

Other teleservices defined are: IS-91 Extended Protocol Enhanced Services, Wireless Paging Teleservice (WPT), Voice Mail Notification (VMN), and Service Category Programming Teleservice (SCPT).

Not all teleservices use all message types: for example, WPT does not support message cancellation, so does not use the Cancellation message type.

Enhanced messaging

The Enhanced Messaging Service (EMS) standard carries pictures, animations, sounds, and rich text in SMS messages.

Wireless Enhanced Messaging Teleservice (WEMT) carries EMS over CDMA SMS.

Character encoding

Alphanumeric text is encoded as 7-bit characters (GSM 03.38).

The encodings used can be specified in the message. Possible encoding types are listed in [3GPP2 C.R1001-C Table 9.1-1].

Point-to-Point\Broadcast

GSM SMS offers a one-to-one and one-to-a-few service.

In addition to a Point-to-Point service, CDMA SMS offers a broadcast service for sending a message to all phones in a defined area.