diff --git a/.coveragerc b/.coveragerc
index 0d79bb02a4a..9a3a52895c3 100644
--- a/.coveragerc
+++ b/.coveragerc
@@ -720,6 +720,7 @@ omit =
     homeassistant/components/mochad/*
     homeassistant/components/modbus/climate.py
     homeassistant/components/modbus/binary_sensor.py
+    homeassistant/components/modem_callerid/button.py
     homeassistant/components/modem_callerid/sensor.py
     homeassistant/components/moehlenhoff_alpha2/__init__.py
     homeassistant/components/moehlenhoff_alpha2/climate.py
diff --git a/homeassistant/components/modem_callerid/__init__.py b/homeassistant/components/modem_callerid/__init__.py
index d66be29f8b7..8f62cf4beb5 100644
--- a/homeassistant/components/modem_callerid/__init__.py
+++ b/homeassistant/components/modem_callerid/__init__.py
@@ -8,7 +8,7 @@ from homeassistant.exceptions import ConfigEntryNotReady
 
 from .const import DATA_KEY_API, DOMAIN, EXCEPTIONS
 
-PLATFORMS = [Platform.SENSOR]
+PLATFORMS = [Platform.BUTTON, Platform.SENSOR]
 
 
 async def async_setup_entry(hass: HomeAssistant, entry: ConfigEntry) -> bool:
diff --git a/homeassistant/components/modem_callerid/button.py b/homeassistant/components/modem_callerid/button.py
new file mode 100644
index 00000000000..63a88a8a4e5
--- /dev/null
+++ b/homeassistant/components/modem_callerid/button.py
@@ -0,0 +1,47 @@
+"""Support for Phone Modem button."""
+from __future__ import annotations
+
+from phone_modem import PhoneModem
+
+from homeassistant.components.button import ButtonEntity
+from homeassistant.config_entries import ConfigEntry
+from homeassistant.const import CONF_DEVICE
+from homeassistant.core import HomeAssistant
+from homeassistant.helpers import entity_platform
+
+from .const import DATA_KEY_API, DOMAIN
+
+
+async def async_setup_entry(
+    hass: HomeAssistant,
+    entry: ConfigEntry,
+    async_add_entities: entity_platform.AddEntitiesCallback,
+) -> None:
+    """Set up the Modem Caller ID sensor."""
+    api = hass.data[DOMAIN][entry.entry_id][DATA_KEY_API]
+    async_add_entities(
+        [
+            PhoneModemButton(
+                api,
+                entry.data[CONF_DEVICE],
+                entry.entry_id,
+            )
+        ]
+    )
+
+
+class PhoneModemButton(ButtonEntity):
+    """Implementation of USB modem caller ID button."""
+
+    _attr_icon = "mdi:phone-hangup"
+    _attr_name = "Phone Modem Reject"
+
+    def __init__(self, api: PhoneModem, device: str, server_unique_id: str) -> None:
+        """Initialize the button."""
+        self.device = device
+        self.api = api
+        self._attr_unique_id = server_unique_id
+
+    async def async_press(self) -> None:
+        """Press the button."""
+        await self.api.reject_call(self.device)
diff --git a/homeassistant/components/modem_callerid/sensor.py b/homeassistant/components/modem_callerid/sensor.py
index 94c7c51ee80..3a1af4aa0a8 100644
--- a/homeassistant/components/modem_callerid/sensor.py
+++ b/homeassistant/components/modem_callerid/sensor.py
@@ -1,6 +1,8 @@
 """A sensor for incoming calls using a USB modem that supports caller ID."""
 from __future__ import annotations
 
+import logging
+
 from phone_modem import PhoneModem
 
 from homeassistant.components.sensor import SensorEntity
@@ -11,6 +13,8 @@ from homeassistant.helpers import entity_platform
 
 from .const import CID, DATA_KEY_API, DOMAIN, ICON, SERVICE_REJECT_CALL
 
+_LOGGER = logging.getLogger(__name__)
+
 
 async def async_setup_entry(
     hass: HomeAssistant,
@@ -42,6 +46,11 @@ async def async_setup_entry(
     platform = entity_platform.async_get_current_platform()
 
     platform.async_register_entity_service(SERVICE_REJECT_CALL, {}, "async_reject_call")
+    _LOGGER.warning(
+        "Calling reject_call service is deprecated and will be removed after 2022.4; "
+        "A new button entity is now available with the same function "
+        "and replaces the existing service"
+    )
 
 
 class ModemCalleridSensor(SensorEntity):