[GP-1111] mPower R. Apr 2021: +CEMODE shall be set to CEMODE=2

Extended the implementation of "getSimCarrierCode" to detect the carrier
(home network) based on the MCC/MNC combination.

Historically mPower used ICCIDs to detect the carrier and apply the
carrier-specific settings. ICCIDs are known for Verizon and AT&T, but
the list of known ICCIDs is not exhaustive.

This change allows the firmware to detect more AT&T SIM cards by using
the MCC/MNC combinations (PLMN IDs) when ICCID is not recognized.

Limitation: The SIM shall be relatively new and report its MNC length,
otherwise MCC/MNC can't be determined and so the carrier code.

2 files changed, 66 insertions, 13 deletions

diff --git a/include/mts/MTS_IO_CellularRadio.h b/include/mts/MTS_IO_CellularRadio.h
index 3783705..daefcd1 100644
--- a/include/mts/MTS_IO_CellularRadio.h
+++ b/include/mts/MTS_IO_CellularRadio.h
@@ -185,6 +185,8 @@ namespace MTS {
 
                 //! Get carrier code based on the SIM card ID (ICCID)
                 virtual CODE getSimCarrierCode(const std::string& sIccid, std::string& sCarrierCode);
+                //! Get carrier code based on the SIM MCC/MNC
+                virtual CODE getSimCarrierCode(const std::string& sMcc, const std::string& sMnc, std::string& sCarrierCode);
 
                 /**
                  * @brief simAccessReadBinary - Read a string of bytes from the SIM Elementary File.
diff --git a/src/MTS_IO_CellularRadio.cpp b/src/MTS_IO_CellularRadio.cpp
index 5b6521f..03baf48 100644
--- a/src/MTS_IO_CellularRadio.cpp
+++ b/src/MTS_IO_CellularRadio.cpp
@@ -935,24 +935,49 @@ ICellularRadio::CODE CellularRadio::unlockSimCard(const Json::Value& jArgs) {
 }
 
 ICellularRadio::CODE CellularRadio::getSimCarrierCode(std::string& sCarrierCode) {
-    std::string sIccid;
     CODE rc;
 
     printTrace("%s| Get carrier code from the SIM card installed", m_sName.c_str());
 
-    rc = getIccid(sIccid);
-    if (rc != SUCCESS) {
-        printError("%s| Unable to determine SIM carrier: Failed to fetch SIM identifier", m_sName.c_str());
-        return rc;
-    }
+    do {
+        // Try to detect based on the ICCID
+        std::string sIccid;
 
-    printTrace("%s| Fetched ICCID: [%s]", m_sName.c_str(), sIccid.c_str());
+        rc = getIccid(sIccid);
+        if (rc != SUCCESS) {
+            printError("%s| Unable to determine SIM carrier: Failed to fetch SIM identifier", m_sName.c_str());
+            break;
+        }
 
-    rc = getSimCarrierCode(sIccid, sCarrierCode);
-    if (rc != SUCCESS) {
-        printError("%s| Unable to determine SIM carrier: Unable to extract carrier from the SIM identifier", m_sName.c_str());
-        return rc;
-    }
+        printTrace("%s| Fetched ICCID: [%s]", m_sName.c_str(), sIccid.c_str());
+
+        rc = getSimCarrierCode(sIccid, sCarrierCode);
+        if (rc != SUCCESS) {
+            printError("%s| Unable to determine SIM carrier: Unable to extract carrier from the SIM identifier", m_sName.c_str());
+            break;
+        }
+
+        if (sCarrierCode != VALUE_UNKNOWN) {
+            rc = SUCCESS;
+            break;
+        }
+
+        // Fallback to the MCC/MNC detection
+        std::string sMcc;
+        std::string sMnc;
+
+        rc = getSimMccMnc(sMcc, sMnc);
+        if (rc != SUCCESS) {
+            printError("%s| Unable to determine SIM carrier: Failed to fetch MCC/MNC from the SIM", m_sName.c_str());
+            break;
+        }
+
+        rc = getSimCarrierCode(sMcc, sMnc, sCarrierCode);
+        if (rc != SUCCESS) {
+            printError("%s| Unable to determine SIM carrier: Unable to extract carrier from MCC/MNC of the SIM", m_sName.c_str());
+            break;
+        }
+    } while(false);
 
     printTrace("%s| Detected carrier code: [%s]", m_sName.c_str(), sCarrierCode.c_str());
     return rc;
@@ -970,13 +995,39 @@ ICellularRadio::CODE CellularRadio::getSimCarrierCode(const std::string& sIccid,
         sCarrierCode = VALUE_CARRIER_CODE_ATT;
     } else {
         // All other carriers for which ICCID prefixes are not defined
-        printWarning("%s| Carrier is unknown for this SIM ID: [%s]", m_sName.c_str(), sIccid.c_str());
+        printWarning("%s| Carrier code is unknown for this SIM ID: [%s]", m_sName.c_str(), sIccid.c_str());
         sCarrierCode = VALUE_UNKNOWN;
     }
 
     return SUCCESS;  // no error cases for now
 }
 
+ICellularRadio::CODE CellularRadio::getSimCarrierCode(const std::string& sMcc, const std::string& sMnc, std::string& sCarrierCode) {
+    const Json::Value& jLookup = MccMncTable::getInstance()->lookup(sMcc, sMnc);
+
+    do {
+        printTrace("%s| MCC-MNC Lookup: [%s][%s][%s]", m_sName.c_str(),
+                   sMcc.c_str(), sMnc.c_str(), jLookup.toStyledString().c_str());
+
+        if (jLookup.isNull()) {
+            printWarning("%s| Carrier code is unknown for this MCC/NNC combination: [%s][%s]", m_sName.c_str(), sMcc.c_str(), sMnc.c_str());
+            sCarrierCode = VALUE_UNKNOWN;
+            break;
+        }
+
+        if (jLookup["carrierCode"].asString().empty()) {
+            printWarning("%s| Carrier code is unknown for this MCC/MNC combination: [%s][%s]", m_sName.c_str(), sMcc.c_str(), sMnc.c_str());
+            sCarrierCode = VALUE_UNKNOWN;
+            break;
+        }
+
+        sCarrierCode = jLookup["carrierCode"].asString();
+        printTrace("%s| Detected carrier code by MCC/MNC: [%s]", m_sName.c_str(), sCarrierCode.c_str());
+    } while (false);
+
+    return CODE::SUCCESS;
+}
+
 ICellularRadio::CODE CellularRadio::simAccessReadBinary(uint16_t iFileId, uint8_t iP1, uint8_t iP2, uint8_t iLe, std::string& sResult) {
     printTrace("%s| Read binary from the SIM Elementary File", m_sName.c_str());