diff --git a/pom.xml b/pom.xml
index 1ed27b5c7..1f6aa9c69 100644
--- a/pom.xml
+++ b/pom.xml
@@ -126,6 +126,13 @@
             <version>0.1.5</version>
         </dependency>
 
+        <dependency>
+            <groupId>com.googlecode.libphonenumber</groupId>
+            <artifactId>libphonenumber</artifactId>
+            <version>8.10.2</version>
+        </dependency>
+
+
         <dependency>
             <groupId>org.glassfish.jersey.test-framework.providers</groupId>
             <artifactId>jersey-test-framework-provider-grizzly2</artifactId>
diff --git a/src/main/java/org/whispersystems/textsecuregcm/controllers/AccountController.java b/src/main/java/org/whispersystems/textsecuregcm/controllers/AccountController.java
index 867eae509..b6081ba54 100644
--- a/src/main/java/org/whispersystems/textsecuregcm/controllers/AccountController.java
+++ b/src/main/java/org/whispersystems/textsecuregcm/controllers/AccountController.java
@@ -127,7 +127,7 @@ public class AccountController {
       throws IOException, RateLimitExceededException
   {
     if (!Util.isValidNumber(number)) {
-      logger.debug("Invalid number: " + number);
+      logger.info("Invalid number: " + number);
       throw new WebApplicationException(Response.status(400).build());
     }
 
diff --git a/src/main/java/org/whispersystems/textsecuregcm/util/Util.java b/src/main/java/org/whispersystems/textsecuregcm/util/Util.java
index 4618bcc95..8164a98a5 100644
--- a/src/main/java/org/whispersystems/textsecuregcm/util/Util.java
+++ b/src/main/java/org/whispersystems/textsecuregcm/util/Util.java
@@ -16,6 +16,8 @@
  */
 package org.whispersystems.textsecuregcm.util;
 
+import com.google.i18n.phonenumbers.PhoneNumberUtil;
+
 import java.io.UnsupportedEncodingException;
 import java.net.URLEncoder;
 import java.security.MessageDigest;
@@ -48,15 +50,7 @@ public class Util {
   }
 
   public static boolean isValidNumber(String number) {
-    return number.matches("^\\+[0-9]{10,}")  ||
-           number.matches("^\\+240[0-9]{6}") ||  // Equatorial Guinea
-           number.matches("^\\+298[0-9]{6}") ||  // Faroe Islands
-           number.matches("^\\+299[0-9]{6}") ||  // Greenland
-           number.matches("^\\+376[0-9]{6}") ||  // Andorra
-           number.matches("^\\+597[0-9]{6}") ||  // Suriname
-           number.matches("^\\+685[0-9]{5}") ||  // Samoa
-           number.matches("^\\+687[0-9]{6}") ||  // New Caledonia
-           number.matches("^\\+689[0-9]{6}");    // French Polynesia     
+    return number.matches("^\\+[0-9]+") && PhoneNumberUtil.getInstance().isPossibleNumber(number, null);
   }
 
   public static String getCountryCode(String number) {
diff --git a/src/test/java/org/whispersystems/textsecuregcm/tests/controllers/AccountControllerTest.java b/src/test/java/org/whispersystems/textsecuregcm/tests/controllers/AccountControllerTest.java
index fa690c402..d924e2903 100644
--- a/src/test/java/org/whispersystems/textsecuregcm/tests/controllers/AccountControllerTest.java
+++ b/src/test/java/org/whispersystems/textsecuregcm/tests/controllers/AccountControllerTest.java
@@ -213,14 +213,14 @@ public class AccountControllerTest {
   public void testSendRestrictedIn() throws Exception {
     Response response =
         resources.getJerseyTest()
-                 .target(String.format("/v1/accounts/sms/code/%s", "+1234567890"))
+                 .target(String.format("/v1/accounts/sms/code/%s", "+12345678901"))
                  .request()
                  .header("X-Forwarded-For", RESTRICTED_HOST)
                  .get();
 
     assertThat(response.getStatus()).isEqualTo(200);
 
-    verify(smsSender).deliverSmsVerification(eq("+1234567890"), eq(Optional.empty()), anyString());
+    verify(smsSender).deliverSmsVerification(eq("+12345678901"), eq(Optional.empty()), anyString());
   }
 
   @Test
diff --git a/src/test/java/org/whispersystems/textsecuregcm/tests/util/ValidNumberTest.java b/src/test/java/org/whispersystems/textsecuregcm/tests/util/ValidNumberTest.java
new file mode 100644
index 000000000..b08822d53
--- /dev/null
+++ b/src/test/java/org/whispersystems/textsecuregcm/tests/util/ValidNumberTest.java
@@ -0,0 +1,47 @@
+package org.whispersystems.textsecuregcm.tests.util;
+
+import org.junit.Test;
+import org.whispersystems.textsecuregcm.util.Util;
+
+import static junit.framework.TestCase.assertTrue;
+import static org.junit.Assert.assertFalse;
+
+public class ValidNumberTest {
+
+  @Test
+  public void testValidE164() {
+    assertTrue(Util.isValidNumber("+14151231234"));
+    assertTrue(Util.isValidNumber("+71234567890"));
+    assertTrue(Util.isValidNumber("+447535742222"));
+    assertTrue(Util.isValidNumber("+4915174108888"));
+  }
+
+  @Test
+  public void testInvalidE164() {
+    assertFalse(Util.isValidNumber("+141512312341"));
+    assertFalse(Util.isValidNumber("+712345678901"));
+    assertFalse(Util.isValidNumber("+4475357422221"));
+    assertFalse(Util.isValidNumber("+491517410888811111"));
+  }
+
+  @Test
+  public void testNotE164() {
+    assertFalse(Util.isValidNumber("+1 415 123 1234"));
+    assertFalse(Util.isValidNumber("+1 (415) 123-1234"));
+    assertFalse(Util.isValidNumber("+1 415)123-1234"));
+    assertFalse(Util.isValidNumber("71234567890"));
+    assertFalse(Util.isValidNumber("001447535742222"));
+    assertFalse(Util.isValidNumber(" +14151231234"));
+    assertFalse(Util.isValidNumber("+1415123123a"));
+  }
+
+  @Test
+  public void testShortRegions() {
+    assertTrue(Util.isValidNumber("+298123456"));
+    assertTrue(Util.isValidNumber("+299123456"));
+    assertTrue(Util.isValidNumber("+376123456"));
+    assertTrue(Util.isValidNumber("+68512345"));
+    assertTrue(Util.isValidNumber("+689123456"));
+  }
+
+}