Cambodia has a comprehensive bus network, and bus travel is cheap and generally of good standard. It's also generally the safest cross-country transportation, aside from flying. Travel from neighboring countries is easy, reliable, and cheap. Buses from Thailand and Vietnam operate daily.
Giant Ibis (3E0, Road 106, Sangkat Doun Penh, Khan Doun Penh, Phnom Penh. 023/987808. www.giantibis.com.)
GST Bus (No. 13, 142 St., Phnom Penh, 12209. 023/218114 or 012/895550.)
Hua Lian (Hua Lian Bus Station, near Olympic Stadium, Phnom Penh. 023/223025.)
Mekong Express (87E0 Sisowath Quay, S.K Wat, Phnom Penh. 023/427518 or 012/257599.)
Neak Krorhorm Travel (127 St. 108, Phnom Penh. 023/219496.)