chan_sip: option 'notifyringing' change and doc fix

In the sample sip.conf this is written with regard to notifyringing:
;notifyringing = no ; Control whether subscriptions already INUSE get sent
RINGING when another call is sent (default: yes)

However, this setting changes whether or not any RINGING indications are sent
to subscriptions. There is no separate configurable setting that allows
to control whether INUSE subscriptions also get sent RINGING. This is however
a useful option, to see (using BLF) if somebody else is able to handle an
incoming call or if everybody is busy.

This patch corrects the documentation for notifyringing (so the documentation
matches the functionality) and make notifyringing a tri-state option, by adding
the value 'notinuse' (in addition to 'yes' and 'no'). When notifyringing =
notinuse, only subscriptions that are not INUSE are sent the RINGING signal.

The default setting for notifyringing remains set to yes, so the default
behaviour is not affected.

ASTERISK-25558

Change-Id: I88f7036ee084bb3f43b74f15612695c6708f74aa

3 files changed, 21 insertions, 6 deletions

diff --git a/channels/chan_sip.c b/channels/chan_sip.c
index 158dc7b18..fa4b864b1 100644
--- a/channels/chan_sip.c
+++ b/channels/chan_sip.c
@@ -14630,7 +14630,7 @@ static void state_notify_build_xml(struct state_notify_data *data, int full, con
 
 	switch (data->state) {
 	case (AST_EXTENSION_RINGING | AST_EXTENSION_INUSE):
-		statestring = (sip_cfg.notifyringing) ? "early" : "confirmed";
+		statestring = (sip_cfg.notifyringing == NOTIFYRINGING_ENABLED) ? "early" : "confirmed";
 		local_state = NOTIFY_INUSE;
 		pidfstate = "busy";
 		pidfnote = "Ringing";
@@ -21120,7 +21120,7 @@ static char *sip_show_settings(struct ast_cli_entry *e, int cmd, struct ast_cli_
 	ast_cli(a->fd, "  Outbound reg. timeout:  %d secs\n", global_reg_timeout);
 	ast_cli(a->fd, "  Outbound reg. attempts: %d\n", global_regattempts_max);
 	ast_cli(a->fd, "  Outbound reg. retry 403:%d\n", global_reg_retry_403);
-	ast_cli(a->fd, "  Notify ringing state:   %s\n", AST_CLI_YESNO(sip_cfg.notifyringing));
+	ast_cli(a->fd, "  Notify ringing state:   %s%s\n", AST_CLI_YESNO(sip_cfg.notifyringing), sip_cfg.notifyringing == NOTIFYRINGING_NOTINUSE ? " (when not in use)" : "");
 	if (sip_cfg.notifyringing) {
 		ast_cli(a->fd, "    Include CID:          %s%s\n",
 				AST_CLI_YESNO(sip_cfg.notifycid),
@@ -31676,7 +31676,11 @@ static int reload_config(enum channelreloadreason reason)
 		} else if (!strcasecmp(v->name, "directrtpsetup")) {
 			sip_cfg.directrtpsetup = ast_true(v->value);
 		} else if (!strcasecmp(v->name, "notifyringing")) {
-			sip_cfg.notifyringing = ast_true(v->value);
+			if (!strcasecmp(v->value, "notinuse")) {
+				sip_cfg.notifyringing = NOTIFYRINGING_NOTINUSE;
+			} else {
+				sip_cfg.notifyringing = ast_true(v->value) ? NOTIFYRINGING_ENABLED : NOTIFYRINGING_DISABLED;
+			}
 		} else if (!strcasecmp(v->name, "notifyhold")) {
 			sip_cfg.notifyhold = ast_true(v->value);
 		} else if (!strcasecmp(v->name, "notifycid")) {
diff --git a/channels/sip/include/sip.h b/channels/sip/include/sip.h
index 87b59f661..d60f49ecb 100644
--- a/channels/sip/include/sip.h
+++ b/channels/sip/include/sip.h
@@ -211,7 +211,7 @@
 #define DEFAULT_ALLOW_EXT_DOM  TRUE    /*!< Allow external domains */
 #define DEFAULT_REALM          "asterisk" /*!< Realm for HTTP digest authentication */
 #define DEFAULT_DOMAINSASREALM FALSE    /*!< Use the domain option to guess the realm for registration and invite requests */
-#define DEFAULT_NOTIFYRINGING  TRUE     /*!< Notify devicestate system on ringing state */
+#define DEFAULT_NOTIFYRINGING  NOTIFYRINGING_ENABLED /*!< Notify devicestate system on ringing state */
 #define DEFAULT_NOTIFYCID      DISABLED	/*!< Include CID with ringing notifications */
 #define DEFAULT_PEDANTIC       TRUE     /*!< Follow SIP standards for dialog matching */
 #define DEFAULT_AUTOCREATEPEER AUTOPEERS_DISABLED    /*!< Don't create peers automagically */
@@ -622,6 +622,13 @@ enum sipmethod {
 	SIP_PING,       /*!< Not supported at all, no standard but still implemented out there */
 };
 
+/*! \brief Setting for the 'notifyringing' option, see sip.conf.sample for details. */
+enum notifyringing_setting {
+	NOTIFYRINGING_DISABLED = 0,
+	NOTIFYRINGING_ENABLED = 1,
+	NOTIFYRINGING_NOTINUSE = 2,
+};
+
 /*! \brief Settings for the 'notifycid' option, see sip.conf.sample for details. */
 enum notifycid_setting {
 	DISABLED       = 0,
diff --git a/configs/samples/sip.conf.sample b/configs/samples/sip.conf.sample
index 0fc5af2ea..fe685141a 100644
--- a/configs/samples/sip.conf.sample
+++ b/configs/samples/sip.conf.sample
@@ -694,8 +694,12 @@ srvlookup=yes                   ; Enable DNS SRV lookups on outbound calls
 ;subscribecontext = default     ; Set a specific context for SUBSCRIBE requests
                                 ; Useful to limit subscriptions to local extensions
                                 ; Settable per peer/user also
-;notifyringing = no             ; Control whether subscriptions already INUSE get sent
-                                ; RINGING when another call is sent (default: yes)
+;notifyringing = no             ; Control when subscriptions get notified of ringing state.
+                                ; Specify 'no' to not send any ringing notifications.
+                                ; Specify 'yes' to always send ringing notifications (default).
+                                ; Specify 'notinuse' to only send ringing notifications for
+                                ; extensions that are not currently in use. This is useful as a
+                                ; visual indication of who is available to pick up an incoming call
 ;notifyhold = yes               ; Notify subscriptions on HOLD state (default: no)
                                 ; Turning on notifyringing and notifyhold will add a lot
                                 ; more database transactions if you are using realtime.