On the Preview site where you can reprint your card, it shows the CO Elite phone number (though they use numbers instead of 866-what it spells).
Of course the number the 1K uses is a better number since it's 800 and ends with 000, so it probably costs them an extra $100 a year, so no wonder they appear to be going with the CO number.
If they use CO's IVR system, that will be another disappointment, as it's horrible.