Asterisk can work behind 2 routers?

Asterisk can run behind 2 routers as i my attached image?And These 3 sip clients can run without any problem? I could not run sip client B. How should i modify asterisk parameters?A and C sip clients are working already

If these are just routers then make sure the routing is actually working between the and the networks by pinging clients from one network to the other. Then make sure that the network is defined on the Asterisk box as a local network in the SIP settings. Otherwise Asterisk may see clients in the network as external and use the public IP.