Hi,
I solve the issue, I write it on following lines (it may helps somebody works)
**http_client** and **my function** use **curl** library as a foundation and I did not use following curl initialization function on my module **mod_init**
`if(curl_global_init(CURL_GLOBAL_ALL)) { LM_ERR("curl_global_init failed\n"); return -1; } `
Interestingly same function works very well on both **Debian 8 + Kamailio** and also FreeSwitch. Later on, I see **FreeSwitch core** handles this curl initialization but Kamailio delegates it to module developer.