Hello Guys,
                I have wrote a trigger on account object that  whenever a user enter duolicate  phone number or email then it will show an error on page and the info will not stored in the account object.
Here is the code

trigger AccountTrigger on Account (before insert, before update)
{
    //Account duplicate protection system.
    if (Trigger.isBefore && (Trigger.isInsert || Trigger.isUpdate))
    {
        Map<String, Account> anAccountMap = new Map<String, Account>();
        for (Account anAccount : System.Trigger.new)
        {
            // Make sure we don't treat an mobile phone that  
            // isn't changing during an update as a duplicate.  
            if ((anAccount.Phone != null) && (Trigger.isInsert || 
                      (anAccount.Phone != Trigger.oldMap.get(anAccount.Id).Phone)))
            {
                // Make sure another new Account isn't also a duplicate  
                if (anAccountMap.containsKey(anAccount.Phone))
                {
                    anAccount.Phone.addError('Another new Account has the same mobile phone.');
                    System.debug('*** Error: found account with dublicate mobile phone: ' + anAccount);
                } else
                {
                    anAccountMap.put(anAccount.Phone, anAccount);
                }
            }
        }  
        // Using a single database query, find all the Accounts in  
        // the database that have the same mobile phone as any  
        // of the Accounts being inserted or updated.  
        for (Account aDBAccount : [SELECT Phone FROM Account WHERE Phone IN :anAccountMap.KeySet()])
        {
            Account newAccount = anAccountMap.get(aDBAccount.Phone);
            newAccount.Phone.addError('An Account with this mobile phone already exists.');
            System.debug('*** Error: found account with dublicate mobile phone: ' + newAccount);
        }
    }
}

Note:-- The thing is that its working but  its not showing any erorr on my particular page. Any help from the MVP's or the consultant  will be great.
Thanx