feat(sip_client): accept DTMF from ATAs on unnegotiated PTs and looser INFO bodies

components/sip_client/README.md

@@ -202,11 +202,15 @@ binary_sensor:
   is reported once when the event starts, independent of the RTP marker bit —
   Yealink DECT handsets (W70B/W73H) and the 3CX Android app send the event
   without it. Repeat packets of the same event, including the retransmitted end
-  packets, do not re-fire the trigger.
-- **SIP INFO** with `application/dtmf-relay` (`Signal=1`) or `application/dtmf`,
-  answered with `200 OK`. `*` and `#` are accepted both literally and as the
-  event codes `10` / `11`. INFO requests outside an established call are
-  answered but do not fire the trigger.
+  packets, do not re-fire the trigger. A 4-byte payload on any other dynamic
+  payload type (96–127) is also taken as a telephone-event, for ATAs that never
+  offer one in their SDP or send it on a different PT than negotiated.
+- **SIP INFO**, answered with `200 OK`. Content types `application/dtmf-relay`,
+  `application/dtmf` and `audio/telephone-event` are accepted, as is a body with
+  no Content-Type at all. The digit is read from a `Signal=` / `d=` / `dtmf=`
+  line or from a body that is nothing but the digit; `*` and `#` are accepted
+  both literally and as the event codes `10` / `11`. INFO requests outside an
+  established call are answered but do not fire the trigger.
 
 In-band audio tones (no telephone-event, no INFO) are **not** decoded.
 

components/sip_client/dtmf.cpp

@@ -40,32 +40,43 @@ char signal_token_to_char(const std::string &token) {
   return is_dtmf_char(c) ? c : 0;
 }
 
-// Value of "Signal=<token>" in a dtmf-relay body. The name is matched
-// case-insensitively; "Duration=" and friends are left alone because the '='
-// must follow the name.
-std::string signal_token(const std::string &body) {
-  std::string lower = to_lower(body);
-  for (size_t p = lower.find("signal"); p != std::string::npos; p = lower.find("signal", p + 6)) {
-    size_t i = p + 6;
-    while (i < body.size() && (body[i] == ' ' || body[i] == '\t')) i++;
-    if (i >= body.size() || body[i] != '=') continue;
-    i++;
-    while (i < body.size() && (body[i] == ' ' || body[i] == '\t')) i++;
-    std::string token;
-    while (i < body.size() && !std::isspace((unsigned char) body[i])) token += body[i++];
-    return token;
-  }
-  return "";
+bool is_dtmf_content_type(const std::string &content_type) {
+  // Empty: gateways that send a body with no Content-Type at all.
+  if (trim(content_type).empty()) return true;
+  std::string type = to_lower(content_type);
+  return type.find("application/dtmf") != std::string::npos ||
+         type.find("audio/telephone-event") != std::string::npos;
+}
+
+// Key of a "<name>=<value>" body line, lowercased; empty when the line has no
+// '=' at all.
+std::string line_key(const std::string &line) {
+  size_t eq = line.find('=');
+  if (eq == std::string::npos) return "";
+  return to_lower(trim(line.substr(0, eq)));
 }
 
 }  // namespace
 
 char parse_dtmf_info(const std::string &content_type, const std::string &body) {
-  // Content-Type may carry parameters, e.g. "application/dtmf-relay;charset=utf-8".
-  std::string type = to_lower(trim(content_type.substr(0, content_type.find(';'))));
-  if (type == "application/dtmf-relay") return signal_token_to_char(signal_token(body));
-  if (type == "application/dtmf") return signal_token_to_char(trim(body));
-  return 0;
+  if (!is_dtmf_content_type(content_type)) return 0;
+  if (body.empty()) return 0;
+
+  // "Signal=1", "d=1" or "dtmf=1" on a line of its own. Other keys, notably
+  // "Duration=250", must not be read as a digit.
+  size_t pos = 0;
+  while (pos < body.size()) {
+    size_t eol = body.find('\n', pos);
+    std::string line = body.substr(pos, eol == std::string::npos ? std::string::npos : eol - pos);
+    std::string key = line_key(line);
+    if (key == "signal" || key == "d" || key == "dtmf")
+      return signal_token_to_char(trim(line.substr(line.find('=') + 1)));
+    if (eol == std::string::npos) break;
+    pos = eol + 1;
+  }
+
+  // No key/value pair: some devices send just the digit as the whole body.
+  return signal_token_to_char(trim(body));
 }
 
 }  // namespace sip_client

components/sip_client/dtmf.h

@@ -1,4 +1,5 @@
 #pragma once
+#include <cstddef>
 #include <cstdint>
 #include <string>
 
@@ -15,6 +16,15 @@ inline char dtmf_event_to_char(uint8_t event) {
   return 0;
 }
 
+// Whether a packet on `pt` should be decoded as a telephone-event even though
+// it is not the negotiated DTMF payload type. Some ATAs send RFC 2833 without
+// ever offering telephone-event in their SDP, or on a different dynamic PT than
+// the one negotiated; a 4-byte payload on a dynamic PT is the telephone-event
+// shape (event, E|R|volume, duration), never an audio frame.
+inline bool is_unnegotiated_telephone_event(uint8_t pt, uint8_t audio_pt, size_t payload_len) {
+  return pt != audio_pt && pt >= 96 && pt <= 127 && payload_len == 4;
+}
+
 inline bool is_dtmf_char(char c) {
   return (c >= '0' && c <= '9') || c == '*' || c == '#' || (c >= 'A' && c <= 'D');
 }
@@ -45,15 +55,18 @@ class DtmfRxDedup {
   uint32_t last_timestamp_{0};
 };
 
-// DTMF carried in a SIP INFO body, as sent by the 3CX Android app and by desk
-// phones configured for "SIP INFO" DTMF. Returns the digit, or 0 when the INFO
-// is not a DTMF INFO.
+// DTMF carried in a SIP INFO body, as sent by the 3CX Android app, by ATAs
+// and by desk phones configured for "SIP INFO" DTMF. Returns the digit, or 0
+// when the INFO is not a DTMF INFO.
 //
 //   application/dtmf-relay:  "Signal=1\r\nDuration=160"
 //   application/dtmf:        "1"
+//   audio/telephone-event:   either shape
 //
-// Senders disagree on how * and # are written -- literally, or as the RFC 4733
-// event codes 10 and 11 -- so both spellings are accepted.
+// The signal is read from a `Signal=` / `d=` / `dtmf=` line, or from a body
+// that is nothing but the digit. Senders disagree on how * and # are written
+// -- literally, or as the RFC 4733 event codes 10 and 11 -- so both spellings
+// are accepted. A body without a Content-Type is parsed too; gateways omit it.
 char parse_dtmf_info(const std::string &content_type, const std::string &body);
 
 }  // namespace sip_client

components/sip_client/rtp_session.cpp

@@ -97,6 +97,7 @@ bool RtpSession::start(uint16_t local_port) {
   this->dtmf_queue_.clear();
   this->dtmf_active_ = false;
   this->dtmf_rx_.reset();
+  this->rx_dtmf_pt_warned_ = false;
   this->last_tx_ms_ = millis();
   // Treat the session start as "just sent audio" so the grace period applies
   // from here; a session with no microphone starts emitting silence right after.
@@ -105,6 +106,10 @@ bool RtpSession::start(uint16_t local_port) {
   this->recv_buf_.resize(1500);
   ESP_LOGI(TAG, "RTP started on port %u (pt=%u %s, dtmf_pt=%d)", local_port,
            this->codec_->desc().pt, this->codec_->desc().rtpmap, this->dtmf_pt_);
+  if (this->dtmf_pt_ < 0) {
+    ESP_LOGW(TAG, "Remote did not negotiate telephone-event (RFC 2833); inbound DTMF "
+                  "relies on SIP INFO or an unnegotiated payload type");
+  }
   return true;
 }
 
@@ -285,9 +290,15 @@ void RtpSession::receive_() {
     size_t header_len = 12 + 4 * (this->recv_buf_[0] & 0x0F);  // CSRC count
     if ((size_t) len <= header_len) continue;
 
-    if (this->dtmf_pt_ >= 0 && pt == (uint8_t) this->dtmf_pt_) {
+    size_t payload_len = (size_t) len - header_len;
+    bool negotiated_dtmf = this->dtmf_pt_ >= 0 && pt == (uint8_t) this->dtmf_pt_;
+    if (negotiated_dtmf || is_unnegotiated_telephone_event(pt, expect_pt, payload_len)) {
+      if (!negotiated_dtmf && !this->rx_dtmf_pt_warned_) {
+        this->rx_dtmf_pt_warned_ = true;
+        ESP_LOGI(TAG, "Accepting inbound DTMF on unnegotiated payload type %u", pt);
+      }
       // RFC 4733 payload: event, E|R|volume, duration (16 bit).
-      if ((size_t) len >= header_len + 4 && this->on_dtmf_) {
+      if (payload_len >= 4 && this->on_dtmf_) {
         uint32_t event_ts = ((uint32_t) this->recv_buf_[4] << 24) |
                             ((uint32_t) this->recv_buf_[5] << 16) |
                             ((uint32_t) this->recv_buf_[6] << 8) | this->recv_buf_[7];

components/sip_client/rtp_session.h

@@ -80,6 +80,7 @@ class RtpSession {
   uint32_t dtmf_timestamp_{0};
   int dtmf_end_packets_{0};
   DtmfRxDedup dtmf_rx_{};
+  bool rx_dtmf_pt_warned_{false};
 
   std::function<void(const int16_t *, size_t)> on_audio_{};
   std::function<void(char)> on_dtmf_{};

tests/native/sip_sdp/README.md

@@ -47,7 +47,9 @@ tests/native/sip_sdp/run.sh
 | `info_star_hash_spellings` | `Signal=*` and `Signal=10`/`11` both accepted |
 | `info_plain_dtmf` | `application/dtmf` bare-digit body |
 | `info_duration_is_not_a_digit` | `Duration=250` must not be read as DTMF `D` |
-| `info_non_dtmf_is_ignored` | other INFO bodies / no Content-Type → no digit |
+| `info_non_dtmf_is_ignored` | other INFO content types / out-of-range codes → no digit |
+| `info_alternate_keys_and_types` | `d=` / `dtmf=` keys, `audio/telephone-event`, missing Content-Type |
+| `unnegotiated_telephone_event_pt` | 4-byte payload on a dynamic PT is DTMF; audio PT and static PTs are not |
 
 ### `G711Codec` (`test_g711_codec.cpp`)
 

tests/native/sip_sdp/test_dtmf.cpp

@@ -5,12 +5,20 @@
 #include <string>
 
 using esphome::sip_client::DtmfRxDedup;
+using esphome::sip_client::is_unnegotiated_telephone_event;
 using esphome::sip_client::parse_dtmf_info;
 
 namespace {
 
 int g_failures = 0;
 
+void require(bool condition, const char *message) {
+  if (!condition) {
+    std::cerr << "FAIL: " << message << '\n';
+    g_failures++;
+  }
+}
+
 void require_eq_char(char actual, char expected, const char *message) {
   if (actual != expected) {
     std::cerr << "FAIL: " << message << " (got '" << (actual == 0 ? '0' : actual)
@@ -101,12 +109,34 @@ void test_info_duration_is_not_a_digit() {
 void test_info_non_dtmf_is_ignored() {
   require_eq_char(parse_dtmf_info("application/media_control+xml", "<vc_primitive/>"), 0,
                   "video fast-update INFO must not fire DTMF");
-  require_eq_char(parse_dtmf_info("", "Signal=1"), 0, "no Content-Type -> no DTMF");
   require_eq_char(parse_dtmf_info("application/dtmf-relay", "Signal=99\r\n"), 0,
                   "out-of-range event code");
   require_eq_char(parse_dtmf_info("application/dtmf-relay", "Signal=\r\n"), 0, "empty signal");
 }
 
+void test_info_alternate_keys_and_types() {
+  // ATAs and gateways vary the key, the type, and whether they send a type at
+  // all; hass-sip accepts all of these and the door relay depends on it.
+  require_eq_char(parse_dtmf_info("application/dtmf-relay", "d=7\r\n"), '7', "d= key");
+  require_eq_char(parse_dtmf_info("application/dtmf-relay", "dtmf=3"), '3', "dtmf= key");
+  require_eq_char(parse_dtmf_info("audio/telephone-event", "Signal=8\r\nDuration=160"), '8',
+                  "audio/telephone-event type");
+  require_eq_char(parse_dtmf_info("", "Signal=1\r\n"), '1', "body with no Content-Type");
+  require_eq_char(parse_dtmf_info("", "6"), '6', "bare digit with no Content-Type");
+}
+
+void test_unnegotiated_telephone_event_pt() {
+  // Some ATAs never offer telephone-event in SDP, or send it on a PT other than
+  // the negotiated one. A 4-byte payload on a dynamic PT is the RFC 4733 shape.
+  require(is_unnegotiated_telephone_event(/*pt=*/96, /*audio_pt=*/0, /*payload_len=*/4),
+          "dynamic PT with a 4-byte payload is a telephone-event");
+  require(is_unnegotiated_telephone_event(127, 8, 4), "top of the dynamic range");
+  require(!is_unnegotiated_telephone_event(96, 96, 4), "the negotiated audio PT is never DTMF");
+  require(!is_unnegotiated_telephone_event(0, 8, 4), "static PTs are not probed");
+  require(!is_unnegotiated_telephone_event(96, 0, 160), "an audio frame is not a telephone-event");
+  require(!is_unnegotiated_telephone_event(96, 0, 3), "a runt payload is not a telephone-event");
+}
+
 }  // namespace
 
 int main() {
@@ -120,6 +150,8 @@ int main() {
   test_info_plain_dtmf();
   test_info_duration_is_not_a_digit();
   test_info_non_dtmf_is_ignored();
+  test_info_alternate_keys_and_types();
+  test_unnegotiated_telephone_event_pt();
 
   if (g_failures != 0) {
     std::cerr << g_failures << " failure(s)\n";