[Users] Two c= tag in sdp body

Hello, I use OpenSer with Cisco AS5300/5350/5400 with IOS 12.3. When Cisco sends an OK 200 SIP message to OpenSer, there are two "c=IN IPV4" tags in sdp body with the same IP address. The nathelper module only replaces the last occurence of c= tag so some SIP clients works wrong because those get the first IP from the first "c=" tag... How can i replace the all occurences of "c=" tag in sdp body with the help of nathelper? Thx, Antal Content-Type: application/sdp. Content-Length: 277. . v=0. o=CiscoSystemsSIP-GW-UserAgent 7144 773 IN IP4 213.253.220.242. s=SIP Call. c=IN IP4 213.253.xxx.xxx. -> this is the original address of Cisco GW t=0 0. m=audio 35944 RTP/AVP 18. c=IN IP4 213.253.xxx.yyy. -> this is the nated address replaced by nathelper a=rtpmap:18 G729/8000. a=fmtp:18 annexb=no. m=video 35946 RTP/AVP. c=IN IP4 213.253.220.253. a=nortpproxy:yes.