Yes, initially I thought about using SMPP for USSD. But it looked really complicated since only few external SMPP libraries have support of USSD and most of that few are in C#/Java/etc. Moreover I didn't have any working software for USSD over SMPP to test interoperability with.
So I decided to use GPRS SUP socket as a simple transport to send MAP-like messages. Workflow of this SUP is very simple and basically it forwards SS messages with little modifications.
On Wed, Nov 25, 2015 at 3:22 PM, Holger Freyther holger@freyther.de wrote:
On 25 Nov 2015, at 12:03, Sergey.Kostanbaev sergey.kostanbaev@gmail.com
wrote:
From: Sergey Kostanbaev sergey.kostanbaev@gmail.com
This series of patches add support for external USSD processing via simplified MAP-like protocol over SUP socket. As an example of a such external application simple USSD to SIP proxy is provided (it targets TS 124 390)
Have you considered using SMPP for USSD? At first this looks more natural than a custom protocol like SUP.
holger