In order to send SMS messages containing ringtones, wallpapers, WAP push or vCards, the content needs to be sent as a binary message. In order to send a binary message to a phone, the User Data Header (UDH) construct must be used. The UDH is a short hexadecimal code which, when received by the handset indicates the type of content contained in the binary message and how to process it. In addition to the UDH, setting the correct Data Coding Scheme (DCS) value, 0x04 or 4 in the case of a binary SMS is also required.
A bind, in the specific case of connecting to Sinch via SMPP, is a single connection using the SMPP protocol. There are three ways to open a connection using SMPP: Transmitter – send short messages to the SMSC and receive responses from SMSC Receiver – receive delivery receipts from the SMSC and return the corresponding responses Transceiver – send and receive messages to and from the SMSC over a single SMPP session.
Bulk SMS is a term used to describe the sending of a large number of messages via an API, usually as part of a marketing campaign. Typically, bulk SMS implies messages are promotional in nature and the company is sending the exact same message to multiple recipients. Bulk SMS is equivalent to Push SMS.