Provide error message when no available account to place a call.

When there is no available phone account to place a call, ensure call
generates an appropriate error message.

Test: Manual
Bug: 120441065
Change-Id: Id46ef60d808ebab03fcf01c27ff871e518a58f99
diff --git a/res/values/strings.xml b/res/values/strings.xml
index eff68a0..da61da8 100644
--- a/res/values/strings.xml
+++ b/res/values/strings.xml
@@ -249,6 +249,12 @@
     <!-- The "decline" button for an incoming call. [CHAR LIMIT=60] -->
     <string name="decline_incoming_call">Decline</string>
 
+    <!-- Error message shown to the user when an outgoing call cannot be placed because there no
+         calling service is present on the device which supports this call type.
+         This is typically encountered when the user tries to dial a SIP/VOIP call, but there are
+         no calling services present which support SIP calling. [CHAR LIMIT=none] -->
+    <string name="cant_call_due_to_no_supported_service">Call cannot be placed because there are no calling accounts which support calls of this type.</string>
+
     <!-- Error message shown to the user when an outgoing call cannot be placed due to an ongoing
          phone call in a third-party app.  For example:
          Call cannot be placed due to your Duo call. [CHAR LIMIT=none] -->