This is not my field of expertise, Im just paraphrasing what I read somewhere else:
Sólo he encontrado algo más o menos explicativo en inglés:
"Einstrahlung" means "Entsendung" from another country to germany -> no insurance necessary in germany
"Ausstrahlung" means "Entsendung" from germany to another country -> german insurance needs to be continued

It´s only a "Entsendung" if you started your job with this company before you came to germany, if your stay in germany was limited by contract and if you are a real employee (no freelancing).

Supongo que es lo que acontece en Alemania con los trabajadores temporarios.

Espero que te sirva para encontrar el término apropiado.