How To Handle Invisible Characters On An Account Number

I am joining on table A AND Table B ON the accountnumber field. The accountnumber on the tblB has some invisble characters at the end, ie "12344 ". The Table A does not have these invisble chars and is "12344".
Due to the extra spaces at the end, the join fails and does not find a match for that acctno. I have used ltrim(rtrim) hoping that will elimante the extra spaces and find a match.
Heres my qry:

select * from Tbla a
inner join tblb B
on ltrim(rtrim(ACCTNO))=ltrim(rtrim(ACCT))

How do I do this, so that it finds a match and returns the acctno.