diff --git a/src/Plugins/BotSharp.Plugin.MongoStorage/Repository/MongoRepository.User.cs b/src/Plugins/BotSharp.Plugin.MongoStorage/Repository/MongoRepository.User.cs
index 8a381069..c2792b23 100644
--- a/src/Plugins/BotSharp.Plugin.MongoStorage/Repository/MongoRepository.User.cs
+++ b/src/Plugins/BotSharp.Plugin.MongoStorage/Repository/MongoRepository.User.cs
@@ -22,7 +22,14 @@ public partial class MongoRepository
             return null;
         }
 
-        phoneSecond = phone.StartsWith("+86") ? phone.Replace("+86", "") : $"+86{phone}";
+        if (regionCode == "CN")
+        {
+            phoneSecond = (phone ?? "").StartsWith("+86") ? (phone ?? "").Replace("+86", "") : ($"+86{phone ?? ""}");
+        }
+        else
+        {
+            phoneSecond = (phone ?? "").Substring(regionCode == "US" ? 2 : 3);
+        }
 
         var user = _dc.Users.AsQueryable().FirstOrDefault(x => (x.Phone == phone || x.Phone == phoneSecond)
         && (x.RegionCode == regionCode || string.IsNullOrWhiteSpace(x.RegionCode))