 static const OTRadioLink::OTRadioChannelConfig RFM23BConfigs[nPrimaryRadioChannels] = {
     // GFSK channel 0 full config, RX/TX, not in itself secure.
     OTRadioLink::OTRadioChannelConfig(OTRFM23BLink::StandardRegSettingsGFSK57600, true), };
+
+
+/**
+ * SIM900 instance
+ */
+// SIM card configs
+static const char SIM900_PIN[5] PROGMEM       = "1111";
+static const char SIM900_APN[] PROGMEM      = "\"mobiledata\""; // GeoSIM
+// UDP Configs - Edit SIM900_UDP_ADDR for relevant server. NOTE: The server IP address should never be committed to GitHub.
+static const char SIM900_UDP_ADDR[16] PROGMEM = ""; // Of form "1.2.3.4".
+static const char SIM900_UDP_PORT[5] PROGMEM = "9999";             // Standard port for OpenTRV servers
+const OTSIM900Link::OTSIM900LinkConfig_t SIM900Config(
+                                                false,
+                                                SIM900_PIN,
+                                                SIM900_APN,
+                                                SIM900_UDP_ADDR,
+                                                SIM900_UDP_PORT);
+OTSIM900Link::OTSIM900Link<8, 5, RADIO_POWER_PIN, OTV0P2BASE::getSecondsLT> SecondaryRadio; // (REGULATOR_POWERUP, RADIO_POWER_PIN);
+
+
 
 /*
  * TMP112 instance

OTV0P2BASE::SupplyVoltageCentiVolts Supply_cV;

/*
 * Radio instance
 */
static constexpr bool RFM23B_allowRX = true;
 

      DEBUG_SERIAL_PRINTLN();
      PrimaryRadio.removeRXMsg();
      }
    SecondaryRadio.poll();

    // =====
    // To sleep, perchance to dream...
