--- channels/chan_sip.c.orig	2009-05-12 21:18:44.000000000 +0300
+++ channels/chan_sip.c	2009-05-26 12:58:10.000000000 +0300
@@ -3061,6 +3061,8 @@
 		} else if (!strcasecmp(ast_var_name(current), "SIPTRANSFER_REPLACES")) {
 			/* We're replacing a call. */
 			p->options->replaces = ast_var_value(current);
+                } else if (!strcasecmp(ast_var_name(current), "SIP_FORCE_CALLID")) {
+                        ast_string_field_set(p, callid, ast_var_value(current));
 		}
 	}