1) You can click the conversation request icon in the Member list.
2) On the right side of the search result profile page, there is a "Connect" button. You'll be able to request conversation by using this button. When your partner is not logged on, this button is not activated.
3) Also in TT4You client, you can click the ID in the list just like you would in the web site, or by using the "connect" button in the search result.
>Receiving calls (Accepting conversation)
When the phone rings, the requester profile is shown on the screen. To accept, click the OK button.