Asterisk: how to get single UserID and register by Authname?

Question

Asterisk

OS: Debian 6.0.9 Squeeze
Asterisk: 1.8.15-cert17
This is a business center and more than two companies are expected to use Asterisk.
In each company, the numbering of calls must begin with 001. Companies can call each other only through the exit to the city line.
In SIP.conf, the numbers are separated only by context
. We tried username, defaultname, auth, authname, fromuser, calerid with the value Context+UserID and a bunch of other things, in all cases an error occurs:

[Jun 17 10:25:58] WARNING[1597]: chan_sip.c:14733 check_auth: username mismatch, have <001>, digest has <0001001>
[Jun 17 10:25:58] NOTICE[1597]: chan_sip.c:25716 handle_request_register: Registration from '<sip:[email protected]>' failed for '10.11.12.13:5060' - Username/auth name mismatch

sip.conf

[001] ; UserID
context = 00001
defaultuser = 00001001
type = friend
secret = 0101
host = dynamic
canreinvite = no
dtmfmode = rfc2833
;mailbox = 001
disallow = all
allow = ulaw
transport = udp

[001]
context = 00002
defaultuser = 00002001
type = friend
secret = 0201
host = dynamic
canreinvite = no
;dtmfmode = rfc2833
disallow = all
allow = ulaw
transport = udp

How to correctly separate organization numbers on one Asterisk? There is information that on Asterisk 1.6 there is a patch that allows separate authorization.
PS: In Asterisk, I'm not a genius, if possible, then a little more in detail about the answers. I'll try not to be stupid. Thank you!

Answer 1

Something like this:
dahdi.conf

; Span 1: WCTDM/0 "Wildcard TDM2400P Board 1" (MASTER) 
;;; line="1 WCTDM/0/0 FXSKS"
signalling=fxs_ks
callerid=asreceived
group=0
context=company-1
echocancel=256
channel => 1

;;; line="2 WCTDM/0/1 FXSKS"
signalling=fxs_ks
callerid=asreceived
group=0
context=company-2
echocancel=256
channel => 2

users.conf

[01001]
cid_number = 001
secret = password1
context=company-1

[02001]
cid_number = 001
secret = password2
context=company-2

extensions.conf

[company-1]
exten => _XXX,1,Dial(SIP/01${EXTEN})
exten => _XXXX!,1,Dial(DAHDI/1/${EXTEN})

[company-2]
exten => _XXX,1,Dial(SIP/02${EXTEN})
exten => _XXXX!,1,Dial(DAHDI/2/${EXTEN})