hi all, I am having problem in ISA for voice communications. I go through all the articles availbale on isaserver and microsoft. and configured the H.323 properly. but there is a strange problem. If users from external send a voice invitation through ISA and Internal user accpet it and it works properly. But if internal user send invitation to external so connection cannot be established. Some PC to Phone like NET2fone and Delta3 is working perfect but one of the other appl i.e., PHONESERVE is not working through ISA. file transfer from internal to external is not working but if any internal user wants to do voice chat within internal user through MSN messenger, so it works. I think some problem with DNS for internet. Internet connection is through LEASED Line. please send me reply about this ASAP thanks Khurram Khan System Engineer Alnafitha IT Tel: +966 2 652 1112 Fax: +966 2 652 8151 Mail to: khurram@xxxxxxxxxxxxx <mailto:khurram@xxxxxxxxxxxxx>