diff --git a/esphome/components/modem/__init__.py b/esphome/components/modem/__init__.py
index 20637a3e1c..ebc3661f26 100644
--- a/esphome/components/modem/__init__.py
+++ b/esphome/components/modem/__init__.py
@@ -22,6 +22,7 @@ CONF_PIN_CODE = "pin_code"
 CONF_APN = "apn"
 CONF_STATUS_PIN = "status_pin"
 CONF_DTR_PIN = "dtr_pin"
+CONF_INIT_AT = "init_at"
 
 
 modem_ns = cg.esphome_ns.namespace("modem")
@@ -44,6 +45,7 @@ CONFIG_SCHEMA = cv.All(
             cv.Optional(CONF_USERNAME): cv.string,
             cv.Optional(CONF_PASSWORD): cv.string,
             cv.Optional(CONF_USE_ADDRESS): cv.string,
+            cv.Optional(CONF_INIT_AT): cv.All(cv.ensure_list(cv.string)),
         }
     ).extend(cv.COMPONENT_SCHEMA),
     cv.require_framework_version(
@@ -90,6 +92,10 @@ async def to_code(config):
     if pin_code := config.get(CONF_PIN_CODE, None):
         cg.add(var.set_pin_code(pin_code))
 
+    if init_at := config.get(CONF_INIT_AT, None):
+        for cmd in init_at:
+            cg.add(var.add_init_at_command(cmd))
+
     cg.add(var.set_model(config[CONF_MODEL]))
     cg.add(var.set_apn(config[CONF_APN]))
 
diff --git a/esphome/components/modem/modem_component.cpp b/esphome/components/modem/modem_component.cpp
index 0eb5dd0897..1f7622f4f5 100644
--- a/esphome/components/modem/modem_component.cpp
+++ b/esphome/components/modem/modem_component.cpp
@@ -15,8 +15,8 @@
 #include <cstring>
 #include <iostream>
 
-static const size_t CONFIG_MODEM_UART_RX_BUFFER_SIZE = 1024;
-static const size_t CONFIG_MODEM_UART_TX_BUFFER_SIZE = 512;
+static const size_t CONFIG_MODEM_UART_RX_BUFFER_SIZE = 2048;
+static const size_t CONFIG_MODEM_UART_TX_BUFFER_SIZE = 1024;
 static const uint8_t CONFIG_MODEM_UART_EVENT_QUEUE_SIZE = 30;
 static const size_t CONFIG_MODEM_UART_EVENT_TASK_STACK_SIZE = 2048;
 static const uint8_t CONFIG_MODEM_UART_EVENT_TASK_PRIORITY = 5;
@@ -152,8 +152,31 @@ void ModemComponent::setup() {
 
   assert(this->dce);
 
-  this->started_ = true;
   this->poweron();
+
+  esp_modem::command_result res;
+  res = this->dce->sync();
+  int retry = 0;
+  while (res != command_result::OK) {
+    res = this->dce->sync();
+    if (res != command_result::OK) {
+      App.feed_wdt();
+      vTaskDelay(pdMS_TO_TICKS(1000));
+    }
+    retry++;
+    if (retry > 20)
+      break;
+  }
+
+  // send initial AT commands from yaml
+  for (const auto &cmd : this->init_at_commands_) {
+    std::string result;
+    command_result err = this->dce->at(cmd.c_str(), result, 1000);
+    delay(100);
+    ESP_LOGI(TAG, "Init AT command: %s (status %d) -> %s", cmd.c_str(), (int) err, result.c_str());
+  }
+
+  this->started_ = true;
   ESP_LOGV(TAG, "Setup finished");
 }
 
@@ -178,21 +201,6 @@ void ModemComponent::start_connect_() {
 
   command_result res = command_result::TIMEOUT;
 
-  // int retry = 0;
-  // while (res != command_result::OK) {
-  //   res = this->dce->sync();
-  //   if (res != command_result::OK) {
-  //     ESP_LOGW(TAG, "modem not responding");
-  //     ESP_LOGI(TAG, "Status: %d", (int) this->get_status());
-  //     this->dce->set_command_mode();
-  //     App.feed_wdt();
-  //     vTaskDelay(pdMS_TO_TICKS(7000));
-  //   }
-  //   retry++;
-  //   if (retry > 10)
-  //     break;
-  // }
-
   res = this->dce->sync();
 
   if (res != command_result::OK) {
diff --git a/esphome/components/modem/modem_component.h b/esphome/components/modem/modem_component.h
index 28565c684f..f747784d00 100644
--- a/esphome/components/modem/modem_component.h
+++ b/esphome/components/modem/modem_component.h
@@ -58,6 +58,7 @@ class ModemComponent : public Component {
   void set_model(const std::string &model) {
     this->model_ = this->modem_model_map_.count(model) ? modem_model_map_[model] : ModemModel::UNKNOWN;
   }
+  void add_init_at_command(const std::string &cmd) { this->init_at_commands_.push_back(cmd); }
   bool get_status() { return gpio_get_level(this->status_pin_); }
   std::unique_ptr<DCE> dce;
 
@@ -73,6 +74,7 @@ class ModemComponent : public Component {
   std::string username_;
   std::string password_;
   std::string apn_;
+  std::vector<std::string> init_at_commands_;
   ModemModel model_;
   std::unordered_map<std::string, ModemModel> modem_model_map_ = {{"BG96", ModemModel::BG96},
                                                                   {"SIM800", ModemModel::SIM800},
diff --git a/tests/test5.1.yaml b/tests/test5.1.yaml
index 848acbe59f..7514057493 100644
--- a/tests/test5.1.yaml
+++ b/tests/test5.1.yaml
@@ -1,5 +1,5 @@
 ---
-# copy of test5.yaml with gsm network
+# copy of test5.yaml with modem network
 esphome:
   name: test5-1
   build_path: build/test5-1
@@ -12,7 +12,7 @@ esp32:
   framework:
     type: esp-idf
 
-gsm:
+modem:
   rx_pin: 26
   tx_pin: 27
   power_pin: 4
@@ -96,7 +96,7 @@ binary_sensor:
     id: modbus_binsensortest
     register_type: read
     address: 0x3200
-    bitmask: 0x80   # (bit 8)
+    bitmask: 0x80 # (bit 8)
     lambda: "return x;"
 
   - platform: tm1638
@@ -646,9 +646,9 @@ display:
     id: primarydisplay
     stb_pin:
       allow_other_uses: true
-      number: 5   # TM1638 STB
-    clk_pin: 18   # TM1638 CLK
-    dio_pin: 23   # TM1638 DIO
+      number: 5 # TM1638 STB
+    clk_pin: 18 # TM1638 CLK
+    dio_pin: 23 # TM1638 DIO
     update_interval: 5s
     intensity: 5
     lambda: |-