[Serusers] Regarding SUBSCRIBE method

hi all, We are getting 408 request timeout for our SUBSCRIBE method inspite of other Useragent sending a 200OK response for the SUBSCRIBE method. Both SUBSCRIBE and 200OK packets are getting proxied to respective user agents correctly. But the client1 is receiving 408 request time out error and the client2 is receiving SUBSCRIBE methods often. The SUBSCRIBE packet and the 200OK packet are as shown below. SUBSCRIBE sip:geetha@192.168.1.9 SIP/2.0 Via: sip/2.0/UDP 192.168.1.22:5060 From: <sip:client1@192.168.1.9>;tag=1050301248710 To: <sip:client2@192.168.1.9> Call-Id: 237f8aec0b47b309dfe8af3d844f9e95(a)192.168.1.22 CSeq: 1 SUBSCRIBE Contact: <sip:192.168.1.22:5060> Expires: 1800 Content-Length: 0 SIP/2.0 200 OK Via: SIP/2.0/UDP 192.168.1.9:5060 Via: SIP/2.0/UDP 192.168.1.22:5060;received=192.168.1.22 From: <sip:client1@192.168.1.9>;tag=1050301248710 To: <sip:client2@192.168.1.9>;tag=1050301221190 Call-Id: 237f8aec0b47b309dfe8af3d844f9e95(a)192.168.1.22 CSeq: 1 SUBSCRIBE Contact: <sip:192.168.1.21:5060> Expires: 1800 Content-Length: 0 Thanks Geetha