diff --git a/configure.ac b/configure.ac
index cce8ab0af4..7932b835ca 100644
--- a/configure.ac
+++ b/configure.ac
@@ -814,6 +814,12 @@ esac
 
 APR_REMOVEFROM(SWITCH_AM_CXXFLAGS, -std=c99)
 
+# check for usable system MD5 library
+AS_CASE([$host],
+  [*-solaris2*], [AC_CHECK_LIB(md5, MD5Init)],
+  [*-freebsd*], [AC_CHECK_LIB(md, MD5Init)],
+  [*-openbsd*|*-netbsd*], [AC_CHECK_FUNCS([MD5Init])])
+
 AC_CHECK_LIB(z, inflateReset, have_libz=yes, AC_MSG_ERROR([no usable zlib; please install zlib devel package or equivalent]))
 if test "x$have_libz" = "xyes"  ; then
 APR_ADDTO([PLATFORM_CORE_LIBS], [-lz])
diff --git a/src/mod/endpoints/mod_sofia/sofia_reg.c b/src/mod/endpoints/mod_sofia/sofia_reg.c
index 7f7d8efba3..30ed7c0f92 100644
--- a/src/mod/endpoints/mod_sofia/sofia_reg.c
+++ b/src/mod/endpoints/mod_sofia/sofia_reg.c
@@ -2692,9 +2692,8 @@ auth_res_t sofia_reg_parse_auth(sofia_profile_t *profile,
 {
 	int indexnum;
 	const char *cur;
-	su_md5_t ctx;
-	char uridigest[2 * SU_MD5_DIGEST_SIZE + 1];
-	char bigdigest[2 * SU_MD5_DIGEST_SIZE + 1];
+	char uridigest[SWITCH_MD5_DIGEST_STRING_SIZE];
+	char bigdigest[SWITCH_MD5_DIGEST_STRING_SIZE];
 	char *username, *realm, *nonce, *uri, *qop, *cnonce, *nc, *response, *input = NULL, *input2 = NULL;
 	auth_res_t ret = AUTH_FORBIDDEN;
 	int first = 0;
@@ -2706,7 +2705,7 @@ auth_res_t sofia_reg_parse_auth(sofia_profile_t *profile,
 	char *sql;
 	char *number_alias = NULL;
 	switch_xml_t user = NULL, param, uparams;
-	char hexdigest[2 * SU_MD5_DIGEST_SIZE + 1] = "";
+	char hexdigest[SWITCH_MD5_DIGEST_STRING_SIZE] = "";
 	char *domain_name = NULL;
 	switch_event_t *params = NULL;
 	const char *auth_acl = NULL;
@@ -3028,10 +3027,7 @@ auth_res_t sofia_reg_parse_auth(sofia_profile_t *profile,
 
 	if (!a1_hash) {
 		input = switch_mprintf("%s:%s:%s", username, realm, passwd);
-		su_md5_init(&ctx);
-		su_md5_strupdate(&ctx, input);
-		su_md5_hexdigest(&ctx, hexdigest);
-		su_md5_deinit(&ctx);
+		switch_md5_string(hexdigest, (void *) input, strlen(input));
 		switch_safe_free(input);
 		a1_hash = hexdigest;
 
@@ -3081,10 +3077,7 @@ auth_res_t sofia_reg_parse_auth(sofia_profile_t *profile,
   for_the_sake_of_interop:
 
 	if ((input = switch_mprintf("%s:%q", regstr, uri))) {
-		su_md5_init(&ctx);
-		su_md5_strupdate(&ctx, input);
-		su_md5_hexdigest(&ctx, uridigest);
-		su_md5_deinit(&ctx);
+		switch_md5_string(uridigest, (void *) input, strlen(input));
 	}
 
 	if (nc && cnonce && qop) {
@@ -3094,11 +3087,7 @@ auth_res_t sofia_reg_parse_auth(sofia_profile_t *profile,
 	}
 
 	if (input2) {
-		memset(&ctx, 0, sizeof(ctx));
-		su_md5_init(&ctx);
-		su_md5_strupdate(&ctx, input2);
-		su_md5_hexdigest(&ctx, bigdigest);
-		su_md5_deinit(&ctx);
+		switch_md5_string(bigdigest, (void *) input2, strlen(input2));
 	}
 
 	if (input2 && !strcasecmp(bigdigest, response)) {
diff --git a/src/switch_apr.c b/src/switch_apr.c
index c0ae265037..daaa2716a1 100644
--- a/src/switch_apr.c
+++ b/src/switch_apr.c
@@ -65,7 +65,13 @@
 /* apr-util headers */
 #include <apr_queue.h>
 #include <apr_uuid.h>
+#if (defined(HAVE_LIBMD5) || defined(HAVE_LIBMD) || defined(HAVE_MD5INIT))
+#include <md5.h>
+#elif defined(HAVE_LIBCRYPTO)
+#include <openssl/md5.h>
+#else
 #include <apr_md5.h>
+#endif
 
 /* apr stubs */
 
@@ -1086,20 +1092,43 @@ SWITCH_DECLARE(switch_status_t) switch_uuid_parse(switch_uuid_t *uuid, const cha
 
 SWITCH_DECLARE(switch_status_t) switch_md5(unsigned char digest[SWITCH_MD5_DIGESTSIZE], const void *input, switch_size_t inputLen)
 {
+#if (defined(HAVE_LIBMD5) || defined(HAVE_LIBMD) || defined(HAVE_MD5INIT))
+	MD5_CTX md5_context;
+
+	MD5Init(&md5_context);
+	MD5Update(&md5_context, input, inputLen);
+	MD5Final(digest, &md5_context);
+
+	return SWITCH_STATUS_SUCCESS;
+#elif defined(HAVE_LIBCRYPTO)
+	MD5_CTX md5_context;
+
+	MD5_Init(&md5_context);
+	MD5_Update(&md5_context, input, inputLen);
+	MD5_Final(digest, &md5_context);
+
+	return SWITCH_STATUS_SUCCESS;
+#else
 	return apr_md5(digest, input, inputLen);
+#endif
 }
 
 SWITCH_DECLARE(switch_status_t) switch_md5_string(char digest_str[SWITCH_MD5_DIGEST_STRING_SIZE], const void *input, switch_size_t inputLen)
 {
 	unsigned char digest[SWITCH_MD5_DIGESTSIZE];
-	apr_status_t status = apr_md5(digest, input, inputLen);
-	int x;
+	switch_status_t status = switch_md5(digest, input, inputLen);
+	short i, x;
+	uint8_t b;
 
 	digest_str[SWITCH_MD5_DIGEST_STRING_SIZE - 1] = '\0';
 
-	for (x = 0; x < SWITCH_MD5_DIGESTSIZE; x++) {
-		switch_snprintf(digest_str + (x * 2), 3, "%02x", digest[x]);
+	for (x = i = 0; x < SWITCH_MD5_DIGESTSIZE; x++) {
+		b = (digest[x] >> 4) & 15;
+		digest_str[i++] = b + (b > 9 ? 'a' - 10 : '0');
+		b = digest[x] & 15;
+		digest_str[i++] = b + (b > 9 ? 'a' - 10 : '0');
 	}
+	digest_str[i] = '\0';
 
 	return status;
 }