asterisk users - Dec 2011 - can't set up tcp sip - sip connection : digest <s> problem

Trying to set up a simple sip - sip connection over tcp. Home : 10.0.0 - 
Office: 1.8.8.0

Home sip.conf:

register => 
tcp://office-going-to-home:password@<office-ipaddr>/home-coming-from-office

[home-coming-from-office]     ; receives  calls
type=friend
transport=tcp
dtmfmode=rfc2833
disallow=all
allow=ulaw
secret=password
context=incoming

Office:
[office-going-to-home]     ;  places calls
type=peer ;; we only call out
transport=tcp
dtmfmode=rfc2833
disallow=all
allow=ulaw
fromuser=home-coming-from-office
remotesecret=password

sip show peer office-going-to-home


   * Name       : office-going-to-home
   Secret       : <Not set>
   MD5Secret    : <Not set>
   Remote Secret: <Set>
........
   Status       : OK (28 ms)
   Useragent    : Asterisk PBX 10.0.0
   Reg. Contact : sip:home-coming-from-office@<home 
ipaddr>:5060;transport=TCP

But if I place a call from the office to home, on home cli:

[Dec 29 16:32:23] WARNING[4387]: chan_sip.c:14446 check_auth: username 
mismatch, have <home-coming-from-office>, digest has <s>
[Dec 29 16:32:23] NOTICE[4387]: chan_sip.c:22769 handle_request_invite: 
Failed to authenticate device "Office" 
<sip:home-coming-from-office@<office ip addr>>;tag=as150d4960

I thought the last part of the register line was supposed to tell the 
calling end point what to put in the digest header.

sean