Onsite interpretation is the most effective form of interpretation, due to the fact that it is conducted face-to-face. Having a professional onsite interpreter physically present allows individuals the advantage of not only hearing but seeing the interpreter and that makes for positive communication and an accurate interpretation. 

On SiteAllowing individuals as well as interpreters to be able to read the body language and facial expressions of one another can only ensure the process run smoothly. 
Sometimes using a telephone interpreter is not suitable, when a situation is delicate or serious in nature then it is best to hire an interpreter that specializes in onsite interpretation.
Having a physical presence can make an individual feel a bit more calm and comfortable in a stressful situation especially when interpretation is involved.