[Serusers] bad udp packet? why!

I installed the ser in Redhat 9.0. I use ngrep to capture the packet.Sometime I got the bad UDP packet send from ser. The following is an example(210.192.101.193 is the ser installed), before MESSAGE sip there are illeagal chars (maybe due to the udp size limit?): U 210.192.101.193:80 -> 218.25.90.134:31500 19036@0:1480 .P{.....MESSAGE sip:lumy1314@218.25.90.134:31500 SIP/2.0..Call-ID: 0f9 ffc6b4dbc35dd8cf153975330c83e@210.192.101.20..CSeq: 1 MESSAGE..From: " miphone" <sip:multichat@sip.miphone.cn:20000;transport=udp>;tag=160203 74..To: <sip:lumy1314@dododoo.com>..Via: SIP/2.0/UDP 210.192.101.193:8 0;branch=z9hG4bKacb8.7ed584b7.0..Via: SIP/2.0/UDP 210.192.101.20:20000 ;branch=z9hG4bK42e5063b387e084e01f8119c4491d60e..Max-Forwards: 69..Con tent-Type: text/x-miphone-multichat..Content-Length: 995..P-hint: usrl oc applied....<?xml version="1.0" encoding="UTF-8"?>.<miphone>.<comman d type="add user">.<from>sip:server</from>.<to>lumy1314@dododoo.com</t o&gt;.&lt;commandcontent&gt;.&lt;roomid&gt;38563504&lt;/roomid&gt;.&lt;sipaddr&gt;hxl(a)email.com.c n</sipaddr>.<name>tuhxl-1</name>.<sex>...</sex>.<age>4</age>.<imageid> 99999</imageid><location></location>.<userauthority>2</userauthority>. <userspeakstatus>NO</userspeakstatus>.<uservideostatus>NO</uservideost atus>.<audioaddr>61.149.14.202</audioaddr>.<audioport>28904</audioport attype>1</nattype>.<firewalladdr></firewalladdr>.<localvideoaddr>61.14 9.14.202</localvideoaddr>.<localvideoport>28914</localvideoport>.<loca laudioaddr>61.149.14.202</localaudioaddr>.<localaudioport>28904</local audioport>.<nowuserlist>.<user>hxl@email.com.cn</user>.<user>tuhxl@mip hone.com.tv</user>.<user>bug@miphone.com.tv</user>.<user>lumy1314@dodo doo.com&lt;/user&gt;.&lt;user&gt;czl(a)dododoo.com&lt;/user&gt;.&lt;/nowuserlist&gt;.&lt;/commandco ntent>.</c