[2] Turning professional in 1998, Phonbun reached the last 48 at that season's China International, recording victories over Joe Delaney, Jason Prince and Darryn Walker before losing 2–5 to Chris Small, and the last 64 at the Welsh Open, where Alain Robidoux defeated him 5–4.

The following season heralded two more last-64 finishes, the most notable being at the 1999 UK Championship, where Phonbun faced Paul Hunter and lost 6–9.

There, his opponents included Kurt Maflin, Nick Dyson, Terry Murphy and Michael Judge, but Graeme Dott eliminated him 5–1.

Phonbun participated in the 2015 Six-red World Championship in Thailand, qualifying from his group with wins over Ben Judge and Ehsan Heydarinezhad but being eliminated in the last 32 by Anthony McGill, who beat him 6–4.

[4][5] He was also invited to play in the 2016 edition of the tournament, but despite victories over Ryan Thomerson and Dominic Dale, defeats to Ding Junhui, Pankaj Advani and Robert Milkins saw him exit at the group stage.