Bus Ticket to Hanoi from Nanning- purchase early?

As I know, the bus tickets for this journey can be bought 15 days ahead. So for convenience, I suggest you buy it in advance. At the same time, you can also get the ticket on the spot on the day of travel. But during Chinese Spring Festival, it may be a little hard to get tickets.

Do you have to purchase tickets at the station or can you call? I currently live in Guangzhou and won't be in Nanning until the day of travel.

Hi, I'm afraid the ticket can only be bought at the local Bus Ticket Agent or bus station.
Once there was a website on which you can book ticket online, but I cannot find it now.

Thank you so much for all of your help!