diff --git a/src/IridiumSBD.cpp b/src/IridiumSBD.cpp
index f7b1c8b..b02ef28 100644
--- a/src/IridiumSBD.cpp
+++ b/src/IridiumSBD.cpp
@@ -171,6 +171,24 @@ void IridiumSBD::adjustATTimeout(int seconds)
    this->atTimeout = seconds;
 }
 
+// Tweak SBD Session Timeout
+int IridiumSBD::adjustSBDSessionTimeout(int seconds)
+{
+   if ((seconds >= this->atTimeout) || seconds == 0)
+      diagprint(F("SBD commands that do not complete before AT timeout will return ISBD_PROTOCOL_ERROR\r\n"));
+
+   if (!this->asleep)
+   {
+      send(F("AT+SBDST="), true, false);
+      send(seconds);
+      send(F("\r"), false);
+      if (!waitForATResponse())
+         return cancelled() ? ISBD_CANCELLED : ISBD_PROTOCOL_ERROR;
+   }
+   this->sbdSessionTimeout = seconds;
+   return ISBD_SUCCESS;
+}
+
 // Tweak Send/Receive SBDIX process timeout
 void IridiumSBD::adjustSendReceiveTimeout(int seconds)
 {
@@ -614,6 +632,21 @@ int IridiumSBD::internalBegin()
    }
    diagprint(F("MSSTM workaround is")); diagprint(msstmWorkaroundRequested ? F("") : F(" NOT")); diagprint(F(" enforced.\r\n"));
 
+   // Set SBD session timeout only if it has been changed from the default (to avoid regressions)
+   // ISU AT Command Reference: "The <timeout> setting is stored only while the SBD Modem is powered up, and defaults to zero (meaning infinite timeout) after a power-cycle."
+   if (this->sbdSessionTimeout != ISBD_DEFAULT_SBDSESSION_TIMEOUT)
+   {
+      ret = adjustSBDSessionTimeout(this->sbdSessionTimeout);
+      if (ret != ISBD_SUCCESS)
+      {
+         diagprint(F("adjustSBDSessionTimeout: failed\r\n"));
+      }
+      else
+      {
+         diagprint(F("adjustSBDSessionTimeout: success!\r\n"));
+      }
+   }
+
    // Done!
    diagprint(F("InternalBegin: success!\r\n"));
    return ISBD_SUCCESS;
diff --git a/src/IridiumSBD.h b/src/IridiumSBD.h
index ebfce06..b2268c2 100644
--- a/src/IridiumSBD.h
+++ b/src/IridiumSBD.h
@@ -67,6 +67,7 @@ Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 #define ISBD_DEFAULT_AT_TIMEOUT         30
 #define ISBD_MSSTM_RETRY_INTERVAL       10
 #define ISBD_DEFAULT_SBDIX_INTERVAL     10
+#define ISBD_DEFAULT_SBDSESSION_TIMEOUT 0
 #define ISBD_USB_SBDIX_INTERVAL         30
 #define ISBD_DEFAULT_SENDRECEIVE_TIME   300
 #define ISBD_STARTUP_MAX_TIME           240
@@ -113,6 +114,7 @@ class IridiumSBD
    typedef enum { DEFAULT_POWER_PROFILE = 0, USB_POWER_PROFILE = 1 } POWERPROFILE;
    void setPowerProfile(POWERPROFILE profile); // 0 = direct connect (default), 1 = USB
    void adjustATTimeout(int seconds);          // default value = 30 seconds
+   int adjustSBDSessionTimeout(int seconds);   // 0 = infinite (default)
    void adjustSendReceiveTimeout(int seconds); // default value = 300 seconds
    void adjustStartupTimeout(int seconds); // default value = 240 seconds
    void useMSSTMWorkaround(bool useMSSTMWorkAround); // true to use workaround from Iridium Alert 5/7/13
@@ -147,6 +149,7 @@ class IridiumSBD
       useSerial = true;
       stream = &str;
       sbdixInterval = ISBD_USB_SBDIX_INTERVAL;
+      sbdSessionTimeout = ISBD_DEFAULT_SBDSESSION_TIMEOUT;
       atTimeout = ISBD_DEFAULT_AT_TIMEOUT;
       sendReceiveTimeout = ISBD_DEFAULT_SENDRECEIVE_TIME;
       startupTimeout = ISBD_STARTUP_MAX_TIME;
@@ -177,6 +180,7 @@ class IridiumSBD
       wireport = &wirePort;
       deviceaddress = deviceAddress;
       sbdixInterval = ISBD_USB_SBDIX_INTERVAL;
+      sbdSessionTimeout = ISBD_DEFAULT_SBDSESSION_TIMEOUT;
       atTimeout = ISBD_DEFAULT_AT_TIMEOUT;
       sendReceiveTimeout = ISBD_DEFAULT_SENDRECEIVE_TIME;
       startupTimeout = ISBD_STARTUP_MAX_TIME;
@@ -217,6 +221,7 @@ class IridiumSBD
 
    // Timings
    int sbdixInterval;
+   int sbdSessionTimeout;
    int atTimeout;
    int sendReceiveTimeout;
    int startupTimeout;