Complex sentence: Many IT and modern marketing companies out source or use white label companies and services to provide specialist services without the need to bring in new staff many of these can liase with the client on your behalf or can contact the client through you.
Split into simpler sentences: Many IT and modern marketing companies out source or use white label companies and services to provide specialist services without the need to bring in new staff. These can liaise with the client on your behalf or can contact the client through you.