phone: display an informational message when no phoneline are set

welco/sources/phone/templates/welco/phone_home.html

@@ -20,6 +20,17 @@
 </div>
 
 <div id="source-mainarea" data-current-calls="{% url 'phone-current-calls' %}">
+{% if not phonelines|length %}
+
+<div class="big-msg-info">
+  {% blocktrans %}
+  You do not have a phoneline configured yet; please enter your identifier in
+  the "Take Phone Line" form on the left.
+  {% endblocktrans %}
+</div>
+
+{% endif %}
+
 {% for phonecall in phonecalls %}
 <div class="phonecall active" data-source-pk="{{phonecall.id}}">
 <h1>{% trans 'Current Call:' %} <strong>{{phonecall.caller}}</strong></h1>

welco/static/css/style.css

@@ -471,3 +471,7 @@ div#takephone button {
 	position: relative;
 	top: -3px;
 }
+
+div#source-mainarea div.big-msg-info {
+	margin-left: 0;
+}