AD B2C Filter user email by mobile phone C#

private async Task GetMailByPhoneNumber(GraphServiceClient graphClient, long mobileNumber) { UserDetailsEntity userDetailsEntity = new UserDetailsEntity(); string mobilePhone = Convert.ToString(mobileNumber); List options = new List { new QueryOption("$count", "true"), new HeaderOption("ConsistencyLevel","eventual") }; var officeUser = await graphClient.Users .Request(options) .Select(e => new { e.DisplayName, e.Mail, e.Id, e.MobilePhone, e.Identities }) .GetAsync(); foreach (var item in officeUser) { if (item.MobilePhone == mobilePhone) { var mail = item.Identities; if (mail != null) { var email = mail.ToDictionary(itemKeySelector => itemKeySelector.IssuerAssignedId); var mailregistered = email.ToArray(); var userMail = mailregistered[0].Key; userDetailsEntity.Email = userMail; userDetailsEntity.ID=item.Id; userDetailsEntity.MobileNumber = mobileNumber; return userDetailsEntity; } } } //if (result != null) //{ // // Console.WriteLine(JsonSerializer.Serialize(result)); //} _responseLogger.Information(new LogEntry() { Message = "START GetMailByPhoneNumber()", TimeStamp = DateTime.UtcNow.ToString(), }); return null; } ================================================== Code Reference: ms-identity-dotnetcore-b2c-account-management-master