SIP call gets the status "Default Status Message" in iOS

Question

I am working on a VOIP app for iOS. and I use the PJSIP library for this. If I make a call using VOIP, I sometimes get the status pj_status_tas the value 320010. And the message "Status message by default", and the call does not connect. Why am I getting this error and how to fix it? I wrote the following.        pj_status_t status;

    if (status != PJ_SUCCESS) {
            const pj_str_t *str = pjsip_get_status_text(status);
            NSString *msg = [[NSString alloc]
                             initWithBytes:str->ptr
                             length:str->slen
                             encoding:[NSString defaultCStringEncoding]];
            [self displayError:msg withTitle:@"Call error"];
}

Any help.