Enroute Controller described a loss of separation event noting some of the coordination relative to this incident was made without utilizing a recorded land line.

Narrative

A CRJ2; filed BAE.EAU8.MSP; climbing to FL330 (my top altitude); requesting FL340. Traffic was two overflight aircraft; both at FL310 and both direct GRR; the second of which was the MD90. I gave the CRJ2 15 degrees left; entered it into the 4th line of the Data Block; and handed him off to HOR (Horicon Super Hi). I coordinated HOR's control leaving FL320 (although not on a recorded line; the sectors are adjacent) and transferred communications. Apparently after checking on with HOR the aircraft requested FL320 as I saw this altitude entered hard in the Data Block. The next time I looked the aircraft were coming together as the CRJ2 appeared to be back on course. I quickly advised the HOR Controller and very shortly thereafter the Conflict Alert went off. I turned the MD90 left to a 060 heading and it appeared that the HOR Controller also went left with the CRJ2; but I believe it was too late to avoid a loss of separation. My only recommendation would be to effect coordination on a recorded line; perhaps this might have helped in this event.