diff --git a/tools/chatgui/tests/test_call_delay.cpp b/tools/chatgui/tests/test_call_delay.cpp
index 3457798d..9e8c404c 100644
--- a/tools/chatgui/tests/test_call_delay.cpp
+++ b/tools/chatgui/tests/test_call_delay.cpp
@@ -143,9 +143,27 @@ static void phase_after_silence() {
     DEBUG_INFO(DEBUG_CATEGORY_CALL, "PASS delay phase: 20 arbitrary initial silence/block combinations converge using cuts only");
 }
 
+static void changing_blocks() {
+    Trial t;
+    const unsigned blocks[] = {1, 191, 192, 193, 575, 576, 577, 768, 960, 1920, 8192};
+    uint64_t next = 0, time = 0;
+    t.available = 48000;
+    for (unsigned tick = 0; tick < 3000; ++tick) {
+        unsigned block = blocks[tick % (sizeof(blocks) / sizeof(blocks[0]))];
+        while (next <= time) { t.available += 960; next += 960; }
+        // Пауза устройства на каждый новый цикл создаёт избыток, затем резерв заставляет выйти из DSP.
+        if (!(tick % 50)) t.available += 48000;
+        unsigned reserve = tick % 50 < 25 ? 960 : (unsigned)(t.available + t.delay.stats().pending + 960);
+        t.pull(block, reserve);
+        time += block;
+    }
+    CHECK(t.boundaries >= 120);
+    DEBUG_INFO(DEBUG_CATEGORY_CALL, "PASS delay changing blocks 1..8192 samples, boundaries=%llu", (unsigned long long)t.boundaries);
+}
+
 int main() {
     debug_config_init(); debug_set_level(DEBUG_LEVEL_INFO);
     for (unsigned block : {240, 480, 777, 960}) for (unsigned phase : {0, 239, 479, 719, 959}) steady(block, phase);
-    switching(); tail_and_reset(); phase_after_silence();
+    switching(); tail_and_reset(); phase_after_silence(); changing_blocks();
     return 0;
 }
diff --git a/tools/chatgui/tests/test_call_jitter.cpp b/tools/chatgui/tests/test_call_jitter.cpp
index f551a98c..f2859941 100644
--- a/tools/chatgui/tests/test_call_jitter.cpp
+++ b/tools/chatgui/tests/test_call_jitter.cpp
@@ -29,6 +29,34 @@ static void push(call_jitter* j, int id, int64_t received_ms = -1) {
     call_jitter_push(j, (const uint8_t*)&id, sizeof(id), (uint32_t)(id * 20), received_ms < 0 ? id * 20 : received_ms, nullptr);
 }
 
+static void test_network_recovery() {
+    for (int block : {240, 480, 777, 960}) {
+        decoder d;
+        auto* j = call_jitter_create(decode, &d, 1000);
+        std::vector<int16_t> output(block);
+        int next = 0, largest_reserve = 0;
+        uint32_t stable_underruns = 0;
+        call_jitter_diagnostics state{};
+        for (int64_t time = 0; time < 30 * 48000; time += block) {
+            // Один перебой 80мс, затем приходит накопленная пачка и продолжается ровная доставка.
+            bool stalled = time >= 48000 && time < 48000 + 3840;
+            while (!stalled && next * 960ll <= time) push(j, next++, time / 48);
+            int n = call_jitter_pull(j, output.data(), block);
+            if (n < block) call_jitter_silence(j, block - n);
+            call_jitter_get_diagnostics(j, &state, 0);
+            largest_reserve = std::max(largest_reserve, state.reserve_ms);
+            if (time < 3 * 48000) stable_underruns = state.underruns;
+            else CHECK(state.underruns == stable_underruns);
+        }
+        CHECK(largest_reserve >= 60 && state.reserve_ms == 20);
+        CHECK(state.delay_mode == 0 && state.phase_samples == 0 && state.tempo_ppm == 1000000);
+        CHECK(state.underruns > 0 && state.underruns <= 2);
+        DEBUG_INFO(DEBUG_CATEGORY_CALL, "recovery block=%d max_reserve=%dms final=%dms phase=%u underruns=%u",
+                   block, largest_reserve, state.reserve_ms, state.phase_samples, state.underruns);
+        call_jitter_destroy(j);
+    }
+}
+
 static void test_audio_clock() {
     const uint64_t id = 987;
     CHECK(call_audio_start(id) == 0);
@@ -116,6 +144,7 @@ int main() {
     debug_set_level(DEBUG_LEVEL_WARN);
     debug_enable_console(1);
     test_audio_clock();
+    test_network_recovery();
     int16_t pcm[480];
     int depth, tempo;
     uint32_t dropped, under;