Pj_ssl_cipher_name: symbol not found error while loading res_pjsip.so on OpenWRT

I am getting the error below while loading res_pjsip.so in asterisk 15 on Openwrt. Can some one please let me know what am I missing?

>>  module load res_pjsip.so

Unable to load module res_pjsip.so
Command 'module load res_pjsip.so' failed.
[Feb 17 09:36:07] WARNING[19228]: loader.c:580 load_dlopen: Error loading module 'res_pjsip.so': Error relocating /usr/lib/asterisk/modules/res_pjsip.so: pj_ssl_cipher_name: symbol not found
[Feb 17 09:36:07] WARNING[19228]: loader.c:1184 load_resource: Module 'res_pjsip.so' could not be loaded.

Are you building PJSIP separately or bundled?