JC International Airlines, the latest service on offer, is certainly cheap, but not necessarily the best flight choice for Phnom Penh to Singapore, according to this travel site.
Note that flights with Silkair or Singapore Airlines to Singapore can be much cheaper and better value if connected to an onward long haul flight.

JC International flies to Singapore
PNOM PENH, 22 January 2018: JC International Airlines, a Cambodian airline owned by Chinese investors will start a daily service to Singapore, later this week, from its home-base Phnom Penh.

Flight QD675 will depart Phnom Penh at 0915 and arrive in Singapore at 1215S. The return flights will depart Singapore at 1255 and arrive in the Cambodian capital at 1355. Timetable information reported by Airlineroute earlier this month. The daily service, commencing 25 January, will use one of its four Airbus A320s with 180 seats.

Making a booking online is not a very user-friendly process. Website content is very basic and the design unattractive with plenty of room for ambiguity in descriptions.

However. a check of flights to Singapore turned up a fare of USD46 one-way.

The Chinese owned airline’s flights and fares are not bookable through Skyscanner a popular comparison site owned by China’s Ctrip.

Skyscanner’s best deal was a USD55 fare on a direct Jetstar Asia flight. The airline offers two daily departures at 1510 and 2015 from Phnom Penh.

Silkair is out of this world with its USD196 one-way fare on the same route. It offers two departure times 0935 and 1825.

Even more expensive, Singapore Airlines’ best one-way was USD326.

JC International flies with the cheapest fare to Singapore, but its website not very reassuring and for USD9 more Jetstar Asia was our choice.
http://www.ttrweekly.com/site/2018/01/j ... singapore/