Some characters like the at-sign, the euro symbol and pound symbol are not displayed correctly on the recipients phone when sending SMS through my SMPP connection. What’s wrong?

Your SMPP provider does not convert these chars to the GSM alphabet automatically. You have to convert the messages to GSM alphabet. To do this, go to Configuration=> Channels, select the SMPP channel and click on the pencil to modify the properties. The Charset setting can be found in the “Advanced Settings” section of the SMPP channel properties. Set this value to “GSM”.