From de5d67ff47cf2e6734b09425d092bdde2a77dd54 Mon Sep 17 00:00:00 2001
From: Chris T <chris@talbothome.com>
Date: Mon, 21 Jun 2021 11:56:58 -0400
Subject: Expand DTD to include information for Visual Voicemail

This commit expands the DTD include settings for visual voicemail (VVM) activation. The two document references are:

[1] https://www.gsma.com/newsroom/wp-content/uploads/2012/07/OMTP_VVM_Specification_1_3.pdf
This is the primary VVM specification

[2] https://source.android.com/devices/tech/config/voicemail
This includes some information that is not obvious from the VVM Specification.

VVM's control signals are over Short Message Service (SMS), and there are (at least) three required settings:
- The VVM Specification ("otmp" is the primary one [1], but [2] notes that there is a second one, "cvvm", and T-Mobile USA is at least one carrier that uses "cvvm"
- The destination visual voicemail number that communicates with the client, and
- The Carrier Prefix, which is the prefix to every VVM control SMS.

With these settings, a VVM client can activate and set up visual voicemail, as all other required settings will be received from the carrier (and thus are not needed in mobile-broadband-provider-info). One such client in development that will use these settings is vvmd:
https://gitlab.com/kop316/vvmd/

To my knowledge, all carriers that have VVM adhere to the VVM OMTP/CVVM standard (as these are the only standards that Android has), and will use settings.
---
 serviceproviders.2.dtd | 19 ++++++++++++++++++-
 1 file changed, 18 insertions(+), 1 deletion(-)

diff --git a/serviceproviders.2.dtd b/serviceproviders.2.dtd
index 37573a6..347378a 100644
--- a/serviceproviders.2.dtd
+++ b/serviceproviders.2.dtd
@@ -11,7 +11,7 @@
 <!-- that piggy-back on the primary provider. -->
 <!ATTLIST provider primary (true|false) #IMPLIED>
 
-<!ELEMENT gsm (network-id*, msisdn-query*, voicemail*, balance-check*, balance-top-up*, apn*)>
+<!ELEMENT gsm (network-id*, msisdn-query*, voicemail*, visual-voicemail*, balance-check*, balance-top-up*, apn*)>
 <!ELEMENT apn (plan*,
                usage?,
                name*,
@@ -32,6 +32,23 @@
 <!-- for historical/legacy reasons network providers may support various alternative -->
 <!-- dial strings that can be used to access voicemail services -->
 
+<!ELEMENT visual-voicemail (standard*,
+                            destination-number*,
+                            carrier-prefix)>
+
+<!ELEMENT standard EMPTY>
+<!ATTLIST standard type (cvvm|otmp) #REQUIRED>
+<!-- Whether the carrier supports OTMP or CVVM for Visual Voicemail -->
+
+<!ELEMENT destination-number (#PCDATA)>
+<!-- This is the destination number to activate/deactivate Visual
+     voicemail over SMS.
+-->
+
+<!ELEMENT carrier-prefix (#PCDATA)>
+<!-- At the beginning of an SMS "Status" or "Sync" message, this will appear.
+-->
+
 <!ELEMENT balance-check (ussd*,
                          dtmf*,
                          sms*,
-- 
cgit v1.2.1


From 4c980003603af8eff1f14defff651c2ffe8ca964 Mon Sep 17 00:00:00 2001
From: Chris T <chris@talbothome.com>
Date: Mon, 21 Jun 2021 11:57:56 -0400
Subject: Include Visual Voicemail Settings for T-Mobile USA

---
 serviceproviders.xml | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/serviceproviders.xml b/serviceproviders.xml
index 31a1629..566014d 100644
--- a/serviceproviders.xml
+++ b/serviceproviders.xml
@@ -13260,6 +13260,11 @@ conceived.
 			<network-id mcc="310" mnc="800"/>
 
 			<voicemail>123</voicemail>
+			<visual-voicemail>
+				<standard type="cvvm"/>
+				<destination-number>127</destination-number>
+				<carrier-prefix>//VVM</carrier-prefix>
+			</visual-voicemail>
 			<apn value="fast.t-mobile.com">
 				<plan type="postpaid"/>
 				<usage type="internet"/>
-- 
cgit v1.2.1