This is another one of those "it depends" situations that Hermes is known for! First-time/infrequent clients at a boutique will not be able to have a leather item shipped (no bags, no belts, no bracelets, etc.). So I guess it makes sense that an SA wouldn't even bother to discuss leather inventory over the phone, since in effect it is not available to the caller. BUT long-term clients (as in those whose store relationship pre-dates the shipping ban) can still get leather products shipped in many cases, with the approval of the manager. And it certainly might be possible to develop an ongoing relationship that will eventually allow phone purchases. Just takes time. And, of course, money. 
