This is for educational purposes only, do not use this method on anyone, as in many jurisdictions there are laws that carry severe penalties for impersonation resulting in damage.
Perhaps the simplest method when it comes to spoofed caller id, this one takes under one minute to pull off and has a 98% success rate overall! All you need is to know where your target works and have the phone number to their workplace. Simply call the target’s number with the phone number of their employer spoofed on their caller id and quickly let them know that they do not need to show up for work today as there has been a schedule change, or even they do not need to show up at the usual time, come in at noon only since major renovations are taking place at the office until then.
End result, the target does not show up for work or shows up late, then when confronted, insists that someone did call him to tell him to not show up or to show up later in the day only. In all cases the employer will believe the target is lying through his teeth, a bad lie to get out of trouble and must have been out partying all night and not caring about his or her responsibilities at the workplace.