asterisk users - Jul 2006 - Cisco 7960 SIP 8-3-0 getting "Got SIP response 400"

After upgrading my phones I now see routine error messages: 
 -- Got SIP response 400 "Bad Request" back from 10.5.1.94

Asterisk SVN-trunk-r7230
Cisco 7960 SIP version 8-3-0. 

Sip show peer:
  * Name       : 14012
  Secret       : <Set>
  MD5Secret    : <Not set>
  Context      : labcm33
  Subscr.Cont. : <Not set>
  Language     : 
  AMA flags    : Unknown
  CallingPres  : Presentation Allowed, Not Screened
  Callgroup    : 
  Pickupgroup  : 
  Mailbox      : 14012
  VM Extension : asterisk
  LastMsgsSent : 0
  Call limit   : 0
  Dynamic      : Yes
  Callerid     : <removed>
  Expire       : 272931
  Insecure     : no
  Nat          : Always
  ACL          : No
  CanReinvite  : Yes
  PromiscRedir : No
  User=Phone   : No
  Trust RPID   : No
  Send RPID    : No
  DTMFmode     : rfc2833
  LastMsg      : 0
  ToHost       : 
  Addr->IP     : 10.5.1.94 Port 5060
  Defaddr->IP  : 0.0.0.0 Port 5060
  Def. Username: 14012
  SIP Options  : (none)
  Codecs       : 0x8000e (gsm|ulaw|alaw|h263)
  Codec Order  : (ulaw,alaw,gsm)
  Status       : Unmonitored
  Useragent    : Cisco-CP7960G/8.0
  Reg. Contact : sip:14012@10.5.1.94:5060;transport=udp
 

 

Any ideas? The phones seem to work fine other than the annoying console
message. Is there some secret setting I can add to my config to stop
this?