Call drop issue for Asterisk

Hello

I have Call issue in Asterisk that asterisk not sending complete calls at a time.
I have SIP from operator and when i am sending 700 calls at a time few of calls are going to MSC while rest are rejecting by asterisk.

Any one can provide help should be appreciated

You would need to provide further information about your configuration and console output, as well as what Asterisk is doing to reject the calls.