Routing problems with 2 Viatalk accounts

I have an interesting (???) routing problem. I have two accounts with Viatalk, registered as follows:

register => FIRST-NUMBER:password1@chicago-1a.vtnoc.net/FIRST-NUMBER
register => SECOND-NUMBER:password2@chicago-1a.vtnoc.net/SECOND-NUMBER

With the following definitions in sip.conf:

[viatalk-1]
type=friend
authuser=FIRST-NUMBER
defaultuser=FIRST-NUMBER
fromuser=FIRST-NUMBER
fromdomain=chicago-1a.vtnoc.net
host=chicago-1a.vtnoc.net
secret=password1
context=incoming-on-vt-1
dtmfmode=inband ; VT uses inband dtmf
allow=ulaw
allow=gsm

[viatalk-2]
type=friend
authuser=SECOND-NUMBER
defaultuser=SECOND-NUMBER
fromuser=SECOND-NUMBER
fromdomain=chicago-1a.vtnoc.net
host=chicago-1a.vtnoc.net
secret=password2
context=incoming-on-vt-2
dtmfmode=inband ; VT uses inband dtmf
allow=ulaw
allow=gsm

The problem is that all incoming calls on number 1 go to the correct context, incoming-on-vt-1, in extensions.conf, but the extension number Asterisk looks for is phone number 2. Since phone number 2 doesn’t exist in the context incoming-on-vt-1, the call gets rejected. Incoming calls on phone number 2 work correctly, i.e. They are routed to incoming-on-vt-2 and the incoming number is phone number 2, so it works correctly as this is the extension number in incoming-on-vt-2.

However, if I change the registration so that they use different Viatalk hosts, e.g.

register => FIRST-NUMBER:password1@chicago-10.vtnoc.net/FIRST-NUMBER
register => SECOND-NUMBER:password2@chicago-1a.vtnoc.net/SECOND-NUMBER

with the corresponding changes in [viatalk-1] and [viatalk-2], then incoming calls on both numbers work correctly. I don’t know if this is an Asterisk problem or a problem with Viatalk, but I would appreciate any suggestions.

Thanks,
Ian.

I forgot to say that I have this problem in Asterisk 1.6.0-beta8 and Asterisk 1.6.0-beta9.

Ian.