res_pjsip: Add DTMF INFO Failback mode

The existing auto dtmf mode reverts to inband if 4733 fails to be
negotiated.  This patch adds a new mode auto_info which will
switch to INFO instead of inband if 4733 is not available.

ASTERISK-27066 #close

Change-Id: Id185b11e84afd9191a2f269e8443019047765e91

contrib/ast-db-manage/config/versions/164abbd708c_add_auto_info_to_endpoint_dtmf_mode.py

@@ -0,0 +1,57 @@
+"""Add auto_info to endpoint dtmf_mode
+
+Revision ID: 164abbd708c
+Revises: 86bb1efa278d
+Create Date: 2017-06-19 13:55:15.354706
+
+"""
+
+# revision identifiers, used by Alembic.
+revision = '164abbd708c'
+down_revision = '86bb1efa278d'
+
+from alembic import op
+import sqlalchemy as sa
+
+OLD_ENUM = ['rfc4733', 'inband', 'info', 'auto']
+NEW_ENUM = ['rfc4733', 'inband', 'info', 'auto', 'auto_info']
+
+old_type = sa.Enum(*OLD_ENUM, name='pjsip_dtmf_mode_values_v2')
+new_type = sa.Enum(*NEW_ENUM, name='pjsip_dtmf_mode_values_v3')
+
+def upgrade():
+    context = op.get_context()
+
+    # Upgrading to this revision WILL clear your directmedia values.
+    if context.bind.dialect.name != 'postgresql':
+        op.alter_column('ps_endpoints', 'dtmf_mode',
+                        type_=new_type,
+                        existing_type=old_type)
+    else:
+        enum = ENUM('rfc4733', 'inband', 'info', 'auto', 'auto_info',
+                    name='pjsip_dtmf_mode_values_v3')
+        enum.create(op.get_bind(), checkfirst=False)
+
+        op.execute('ALTER TABLE ps_endpoints ALTER COLUMN dtmf_mode TYPE'
+                   ' pjsip_dtmf_mode_values_v3 USING'
+                   ' dtmf_mode::text::pjsip_dtmf_mode_values_v3')
+
+        ENUM(name="pjsip_dtmf_mode_values_v2").drop(op.get_bind(), checkfirst=False)
+
+def downgrade():
+    context = op.get_context()
+
+    if context.bind.dialect.name != 'postgresql':
+        op.alter_column('ps_endpoints', 'dtmf_mode',
+                        type_=old_type,
+                        existing_type=new_type)
+    else:
+        enum = ENUM('rfc4733', 'inband', 'info', 'auto',
+                    name='pjsip_dtmf_mode_values_v2')
+        enum.create(op.get_bind(), checkfirst=False)
+
+        op.execute('ALTER TABLE ps_endpoints ALTER COLUMN dtmf_mode TYPE'
+                   ' pjsip_dtmf_mode_values USING'
+                   ' dtmf_mode::text::pjsip_dtmf_mode_values_v2')
+
+        ENUM(name="pjsip_dtmf_mode_values_v3").drop(op.get_bind(), checkfirst=False)