EDIT: I think this is not actually the same number I called - see new post later in this thread. The number I used is +65 6336-3371.

ORIGINAL POST: I can confirm this number works and sends you directly to the SIN call centre.

I was recently in Singapore and had successfully applied a GUC to my return journey, but the ticket reissue hadn't happened so I couldn't check in. (Side note - why is this STILL happening? How hard is it to make sure all tickets get reissued before day of departure? Sigh...)

I called the Singapore number rather than the Diamond line so it would be a local call. I reached an agent with a distinctly Singaporean accent; I was able to tell her my ticket needed to be reissued so I could check in, and she was able to do it very quickly - without the usual long hold time, so I'm pretty sure she didn't call IRRRES like usually happens with US-based agents.

I did have to wait on hold a bit even after entering my SkyMiles number, though, so I wouldn't necessarily say calling Singapore directly is a better option than just calling the elite line, describing your problem, and asking to be transferred to the international reissue desk. I do think it would be a better option for someone with no status vs. calling the general line, however.