diff --git a/services/identity/src/database/device_list.rs b/services/identity/src/database/device_list.rs
index c9a0e1c84..190e583cb 100644
--- a/services/identity/src/database/device_list.rs
+++ b/services/identity/src/database/device_list.rs
@@ -1,342 +1,385 @@
 // TODO: get rid of this
 #![allow(dead_code)]
 
 use std::collections::HashMap;
 
 use aws_sdk_dynamodb::model::AttributeValue;
 use chrono::{DateTime, Utc};
-use tracing::warn;
+use tracing::{error, warn};
 
 use crate::{
-  constants::devices_table::*,
+  constants::{
+    devices_table::*, USERS_TABLE,
+    USERS_TABLE_DEVICELIST_TIMESTAMP_ATTRIBUTE_NAME, USERS_TABLE_PARTITION_KEY,
+  },
   database::parse_string_attribute,
   ddb_utils::AttributesOptionExt,
-  error::{DBItemAttributeError, DBItemError, FromAttributeValue},
+  error::{DBItemAttributeError, DBItemError, Error, FromAttributeValue},
   grpc_services::protos::unauth::DeviceType,
 };
 
+use super::parse_date_time_attribute;
+
 type RawAttributes = HashMap<String, AttributeValue>;
 
 #[derive(Clone, Debug)]
 pub enum DevicesTableRow {
   Device(DeviceRow),
   DeviceList(DeviceListRow),
 }
 
 #[derive(Clone, Debug)]
 pub struct DeviceRow {
   pub user_id: String,
   pub device_id: String,
   pub device_type: DeviceType,
   pub device_key_info: IdentityKeyInfo,
   pub content_prekey: PreKey,
   pub notif_prekey: PreKey,
 }
 
 #[derive(Clone, Debug)]
 pub struct DeviceListRow {
   pub user_id: String,
   pub timestamp: DateTime<Utc>,
   pub device_ids: Vec<String>,
 }
 
 #[derive(Clone, Debug)]
 pub struct IdentityKeyInfo {
   pub key_payload: String,
   pub key_payload_signature: String,
   pub social_proof: Option<String>,
 }
 
 #[derive(Clone, Debug)]
 pub struct PreKey {
   pub pre_key: String,
   pub pre_key_signature: String,
 }
 
 // helper structs for converting to/from attribute values for sort key (a.k.a itemID)
 struct DeviceIDAttribute(String);
 struct DeviceListKeyAttribute(DateTime<Utc>);
 
 impl From<DeviceIDAttribute> for AttributeValue {
   fn from(value: DeviceIDAttribute) -> Self {
     AttributeValue::S(format!("{DEVICE_ITEM_KEY_PREFIX}{}", value.0))
   }
 }
 
 impl From<DeviceListKeyAttribute> for AttributeValue {
   fn from(value: DeviceListKeyAttribute) -> Self {
     AttributeValue::S(format!(
       "{DEVICE_LIST_KEY_PREFIX}{}",
       value.0.to_rfc3339()
     ))
   }
 }
 
 impl TryFrom<Option<AttributeValue>> for DeviceIDAttribute {
   type Error = DBItemError;
   fn try_from(value: Option<AttributeValue>) -> Result<Self, Self::Error> {
     let item_id = parse_string_attribute(ATTR_ITEM_ID, value)?;
 
     // remove the device- prefix
     let device_id = item_id
       .strip_prefix(DEVICE_ITEM_KEY_PREFIX)
       .ok_or_else(|| DBItemError {
         attribute_name: ATTR_ITEM_ID.to_string(),
         attribute_value: Some(AttributeValue::S(item_id.clone())),
         attribute_error: DBItemAttributeError::InvalidValue,
       })?
       .to_string();
 
     Ok(Self(device_id))
   }
 }
 
 impl TryFrom<Option<AttributeValue>> for DeviceListKeyAttribute {
   type Error = DBItemError;
   fn try_from(value: Option<AttributeValue>) -> Result<Self, Self::Error> {
     let item_id = parse_string_attribute(ATTR_ITEM_ID, value)?;
 
     // remove the device-list- prefix, then parse the timestamp
     let timestamp: DateTime<Utc> = item_id
       .strip_prefix(DEVICE_LIST_KEY_PREFIX)
       .ok_or_else(|| DBItemError {
         attribute_name: ATTR_ITEM_ID.to_string(),
         attribute_value: Some(AttributeValue::S(item_id.clone())),
         attribute_error: DBItemAttributeError::InvalidValue,
       })
       .and_then(|s| {
         s.parse().map_err(|e| {
           DBItemError::new(
             ATTR_ITEM_ID.to_string(),
             Some(AttributeValue::S(item_id.clone())),
             DBItemAttributeError::InvalidTimestamp(e),
           )
         })
       })?;
 
     Ok(Self(timestamp))
   }
 }
 
 impl TryFrom<RawAttributes> for DeviceRow {
   type Error = DBItemError;
 
   fn try_from(mut attrs: RawAttributes) -> Result<Self, Self::Error> {
     let user_id =
       parse_string_attribute(ATTR_USER_ID, attrs.remove(ATTR_USER_ID))?;
     let DeviceIDAttribute(device_id) = attrs.remove(ATTR_ITEM_ID).try_into()?;
 
     let raw_device_type =
       parse_string_attribute(ATTR_DEVICE_TYPE, attrs.remove(ATTR_DEVICE_TYPE))?;
     let device_type =
       DeviceType::from_str_name(&raw_device_type).ok_or_else(|| {
         DBItemError::new(
           ATTR_DEVICE_TYPE.to_string(),
           Some(AttributeValue::S(raw_device_type)),
           DBItemAttributeError::InvalidValue,
         )
       })?;
 
     let device_key_info = attrs
       .remove(ATTR_DEVICE_KEY_INFO)
       .ok_or_missing(ATTR_DEVICE_KEY_INFO)?
       .to_hashmap(ATTR_DEVICE_KEY_INFO)
       .cloned()
       .and_then(IdentityKeyInfo::try_from)?;
 
     let content_prekey = attrs
       .remove(ATTR_CONTENT_PREKEY)
       .ok_or_missing(ATTR_CONTENT_PREKEY)?
       .to_hashmap(ATTR_CONTENT_PREKEY)
       .cloned()
       .and_then(PreKey::try_from)?;
 
     let notif_prekey = attrs
       .remove(ATTR_NOTIF_PREKEY)
       .ok_or_missing(ATTR_NOTIF_PREKEY)?
       .to_hashmap(ATTR_NOTIF_PREKEY)
       .cloned()
       .and_then(PreKey::try_from)?;
 
     Ok(Self {
       user_id,
       device_id,
       device_type,
       device_key_info,
       content_prekey,
       notif_prekey,
     })
   }
 }
 
 impl From<DeviceRow> for RawAttributes {
   fn from(value: DeviceRow) -> Self {
     HashMap::from([
       (ATTR_USER_ID.to_string(), AttributeValue::S(value.user_id)),
       (
         ATTR_ITEM_ID.to_string(),
         DeviceIDAttribute(value.device_id).into(),
       ),
       (
         ATTR_DEVICE_TYPE.to_string(),
         AttributeValue::S(value.device_type.as_str_name().to_string()),
       ),
       (
         ATTR_DEVICE_KEY_INFO.to_string(),
         value.device_key_info.into(),
       ),
       (ATTR_CONTENT_PREKEY.to_string(), value.content_prekey.into()),
       (ATTR_NOTIF_PREKEY.to_string(), value.notif_prekey.into()),
     ])
   }
 }
 
 impl From<IdentityKeyInfo> for AttributeValue {
   fn from(value: IdentityKeyInfo) -> Self {
     let mut attrs = HashMap::from([
       (
         ATTR_KEY_PAYLOAD.to_string(),
         AttributeValue::S(value.key_payload),
       ),
       (
         ATTR_KEY_PAYLOAD_SIGNATURE.to_string(),
         AttributeValue::S(value.key_payload_signature),
       ),
     ]);
     if let Some(social_proof) = value.social_proof {
       attrs.insert(
         ATTR_SOCIAL_PROOF.to_string(),
         AttributeValue::S(social_proof),
       );
     }
     AttributeValue::M(attrs)
   }
 }
 
 impl TryFrom<RawAttributes> for IdentityKeyInfo {
   type Error = DBItemError;
   fn try_from(mut attrs: RawAttributes) -> Result<Self, Self::Error> {
     let key_payload =
       parse_string_attribute(ATTR_KEY_PAYLOAD, attrs.remove(ATTR_KEY_PAYLOAD))?;
     let key_payload_signature = parse_string_attribute(
       ATTR_KEY_PAYLOAD_SIGNATURE,
       attrs.remove(ATTR_KEY_PAYLOAD_SIGNATURE),
     )?;
     // social proof is optional
     let social_proof = attrs
       .remove(ATTR_SOCIAL_PROOF)
       .map(|attr| attr.to_string(ATTR_SOCIAL_PROOF).cloned())
       .transpose()?;
 
     Ok(Self {
       key_payload,
       key_payload_signature,
       social_proof,
     })
   }
 }
 
 impl From<PreKey> for AttributeValue {
   fn from(value: PreKey) -> Self {
     let attrs = HashMap::from([
       (ATTR_PREKEY.to_string(), AttributeValue::S(value.pre_key)),
       (
         ATTR_PREKEY_SIGNATURE.to_string(),
         AttributeValue::S(value.pre_key_signature),
       ),
     ]);
     AttributeValue::M(attrs)
   }
 }
 
 impl TryFrom<RawAttributes> for PreKey {
   type Error = DBItemError;
   fn try_from(mut attrs: RawAttributes) -> Result<Self, Self::Error> {
     let pre_key =
       parse_string_attribute(ATTR_PREKEY, attrs.remove(ATTR_PREKEY))?;
     let pre_key_signature = parse_string_attribute(
       ATTR_PREKEY_SIGNATURE,
       attrs.remove(ATTR_PREKEY_SIGNATURE),
     )?;
     Ok(Self {
       pre_key,
       pre_key_signature,
     })
   }
 }
 
 impl TryFrom<RawAttributes> for DeviceListRow {
   type Error = DBItemError;
 
   fn try_from(mut attrs: RawAttributes) -> Result<Self, Self::Error> {
     let user_id =
       parse_string_attribute(ATTR_USER_ID, attrs.remove(ATTR_USER_ID))?;
     let DeviceListKeyAttribute(timestamp) =
       attrs.remove(ATTR_ITEM_ID).try_into()?;
 
     // validate timestamps are in sync
     let timestamps_match = attrs
       .remove(ATTR_TIMESTAMP)
       .and_then(|attr| attr.as_n().ok().cloned())
       .and_then(|val| val.parse::<i64>().ok())
       .filter(|val| *val == timestamp.timestamp_millis())
       .is_some();
     if !timestamps_match {
       warn!(
         "DeviceList timestamp mismatch for (userID={}, itemID={})",
         &user_id,
         timestamp.to_rfc3339()
       );
     }
 
     // this should be a list of strings
     let device_ids = attrs
       .remove(ATTR_DEVICE_IDS)
       .ok_or_else(|| {
         DBItemError::new(
           ATTR_DEVICE_IDS.to_string(),
           None,
           DBItemAttributeError::Missing,
         )
       })?
       .to_vec(ATTR_DEVICE_IDS)?
       .iter()
       .map(|v| v.to_string("device_ids[?]").cloned())
       .collect::<Result<Vec<String>, DBItemError>>()?;
 
     Ok(Self {
       user_id,
       timestamp,
       device_ids,
     })
   }
 }
 
 impl From<DeviceListRow> for RawAttributes {
   fn from(device_list: DeviceListRow) -> Self {
     let mut attrs = HashMap::new();
     attrs.insert(
       ATTR_USER_ID.to_string(),
       AttributeValue::S(device_list.user_id.clone()),
     );
     attrs.insert(
       ATTR_ITEM_ID.to_string(),
       DeviceListKeyAttribute(device_list.timestamp).into(),
     );
     attrs.insert(
       ATTR_TIMESTAMP.to_string(),
       AttributeValue::N(device_list.timestamp.timestamp_millis().to_string()),
     );
     attrs.insert(
       ATTR_DEVICE_IDS.to_string(),
       AttributeValue::L(
         device_list
           .device_ids
           .into_iter()
           .map(AttributeValue::S)
           .collect(),
       ),
     );
     attrs
   }
 }
+
+/// Gets timestamp of user's current device list. Returns None if the user
+/// doesn't have a device list yet. Storing the timestamp in the users table is
+/// required for consistency. It's used as a condition when updating the device
+/// list.
+async fn get_current_devicelist_timestamp(
+  db: &crate::database::DatabaseClient,
+  user_id: impl Into<String>,
+) -> Result<Option<DateTime<Utc>>, Error> {
+  let response = db
+    .client
+    .get_item()
+    .table_name(USERS_TABLE)
+    .key(USERS_TABLE_PARTITION_KEY, AttributeValue::S(user_id.into()))
+    .projection_expression(USERS_TABLE_DEVICELIST_TIMESTAMP_ATTRIBUTE_NAME)
+    .send()
+    .await
+    .map_err(|e| {
+      error!("Failed to get user's device list timestamp: {:?}", e);
+      Error::AwsSdk(e.into())
+    })?;
+
+  let mut user_item = response.item.unwrap_or_default();
+  let raw_datetime =
+    user_item.remove(USERS_TABLE_DEVICELIST_TIMESTAMP_ATTRIBUTE_NAME);
+
+  // existing records will not have this field when
+  // updating device list for the first time
+  if raw_datetime.is_none() {
+    return Ok(None);
+  }
+
+  let timestamp = parse_date_time_attribute(
+    USERS_TABLE_DEVICELIST_TIMESTAMP_ATTRIBUTE_NAME,
+    raw_datetime,
+  )?;
+  Ok(Some(timestamp))
+}