Hello All, I think in function respond_digest (), operation for AKAv2 is missing. To add operation for AKAv2, the beginning part of this function should be as follow: static pj_status_t respond_digest( pj_pool_t *pool, pjsip_digest_credential *cred, const pjsip_digest_challenge *chal, const pj_str_t *uri, const pjsip_cred_info *cred_info, const pj_str_t *cnonce, pj_uint32_t nc, const pj_str_t *method) { const pj_str_t pjsip_AKAv1_MD5_STR = { "AKAv1-MD5", 9 }; const pj_str_t pjsip_AKAv2_MD5_STR = { "AKAv2-MD5", 9 }; /* Check algorithm is supported. We support MD5 and AKAv1-MD5. */ if (chal->algorithm.slen==0 || (pj_stricmp(&chal->algorithm, &pjsip_MD5_STR)==0 || pj_stricmp(&chal->algorithm, &pjsip_AKAv1_MD5_STR)==0 || pj_stricmp(&chal->algorithm, &pjsip_AKAv2_MD5_STR)==0)) { ; } Best Regards, Kunimitsu Arai