I have never given an altar call or invitation as such, nor have I seen anyone else do it. Most of the saints of God who have passed on to glory had previously requested that the gospel be preached for they knew their unsaved loved ones would be there. After a gospel message or an appropriate message, it is usually concluded along the lines of "if there is any here who has a spiritual need and would like to talk to me or one of the pastors present be sure to meet with me after the service." That is as much as an invitation as I have heard at a funeral.