Why did Anton Chigurh answer the phone?

In this scene from No Country for Old Men, Carson Wells and Anton Chigurh converse in a hotel room. The phone rings about the time that Chigurh kills Wells.

Answering the phone is a high-risk activity that could implicate Chigurh in Wells' murder. The police could estimate the time of death. If the phone company kept call logs in 1979, the police could obtain those logs and learn the call occurred the same moment that Wells died.

A separate high-risk activity is talking to Llewellyn Moss, threatening his wife, and providing crucial details to Moss about possible next actions. When Llewellyn Moss hears Chigurh threaten his wife, he could decide to inform the police not only where Chigurh is at that moment but where Chigurh plans to go soon. (Clearly Chigurh deduced that Llewellyn Moss would not inform the police, and his gamble paid off, but still there was the risk of that.)

All in all, three actions of answering the phone, threatening to kill Moss' wife, and letting Moss know where Chigurh is going next are each very risky.

There is also a separate question of how Chigurh would know where to find Carla Jean Moss, but that can be asked in a different post.

One might think Chigurh answers the phone to obtain information, but he does not need to. He already knows that Llewellyn Moss is in the hospital across the street, that Carla Jean Moss is hiding somewhere, and that the money is not with Llewellyn Moss at that moment. He makes an offer to Moss: you hand over the money and your wife lives, but you will die anyway. If he anticipated that Moss was the person calling for Carson Wells, he has no need to convey that offer over the phone because he has sufficient knowledge of Moss's whereabouts to convey the offer through other means, means that are less risky.

Why did he answer the phone? Why did he engage in other high risk actions on the phone?

Answers from the book or the movie are acceptable.