In this paper, we study the $$M_n/M_n/c/(K_1+K_2)+M_n$$ system with two finite-size queues where underlying exponential random variables have state-dependent rates. When all servers are busy, upon arrival customers may join online or offline/callback queue simply balk. Customers waiting in impatient and if their patience expires, they choose to callback instead of abandoning for good. assumed b...