Schlechtriem, Peter (ed.), English Commentary on the UN Convention on the International Sale of Goods (CISG), Comment on Art. 18 by Peter Schlechtriem, Oxford 1998

9" Silence. Silence or inactivity can in principle also express an intention to accept; there is then of course no question of its 'reaching' the addressee. However, for such conduct to indicate assent, there must be additional factors associated with the silence or inactivity. The possibility that silence may indicate assent does not mean that an offeror can insert a term to that effect in the offer as a way of binding the offeree if he fails to reply to the offer.38

38Bianca/Bonell/Farnsworth, Art 18, note 2.3; Sutton, (1977) 16 U W Ont L Rev 121; an ULF See Art 2(2), also Dölle/Schlechtriem, Art 6 EAG, paras 36, 37