Don't 'use my own number' if user doesn't have one

app/main/views/send.py

@@ -410,7 +410,8 @@ def send_test_step(service_id, template_id, step_index):
     if (
         request.endpoint == 'main.send_one_off_step' and
         step_index == 0 and
-        template.template_type != 'letter'
+        template.template_type != 'letter' and
+        not (template.template_type == 'sms' and current_user.mobile_number is None)
     ):
         skip_link = (
             'Use my {}'.format(first_column_headings[template.template_type][0]),

tests/app/main/views/test_send.py

@@ -660,7 +660,6 @@ def test_send_one_off_has_skip_link(
     expected_link_text,
     expected_link_url,
 ):
-
     template_mock(mocker)
     mocker.patch('app.main.views.send.get_page_count_for_letter', return_value=99)
 
@@ -683,6 +682,23 @@ def test_send_one_off_has_skip_link(
         assert not skip_links
 
 
+def test_skip_link_will_not_show_on_sms_one_off_if_service_has_no_mobile_number(
+    logged_in_client,
+    service_one,
+    fake_uuid,
+    mock_get_service_template,
+    active_user_with_permissions
+):
+    active_user_with_permissions.mobile_number = None
+    response = logged_in_client.get(
+        url_for('main.send_one_off_step', service_id=service_one['id'], template_id=fake_uuid, step_index=0),
+        follow_redirects=True
+    )
+    page = BeautifulSoup(response.data.decode('utf-8'), 'html.parser')
+    skip_links = page.select('a.top-gutter-4-3')
+    assert not skip_links
+
+
 @pytest.mark.parametrize('endpoint, expected_redirect, placeholders', [
     (
         'main.send_test_step',