Connecting 3 Servers with IAX2 Trunks

We have connected, with the following configuration 3 sites ,(kavala,athens,sindos) through vpn and for the last 2 months all the sites were talking to each other,until yesterday morning 12:00 hours that kavala made the last call to the other sites.
The connection between sindos & athens is working fine . The trunks from sindos & athens to kavala are unavailable.
We delete the trunks from all the sites and we created the trunks again beggining from kavala with sindos & athens.
It didn’t work. Then we created the trunks between sindos & athens and the trunks are working fine as before. Kavala trunks
are unavailable. The servers are pinging one another. Bellow is the trunk configuration .

InterCompany Trunks

Sindos Elastix

To Kavala

Trunk Name: kavala
Peer Details

username=kavala
type=friend
trunk=yes
secret=asco
qualify=yes
host=192.168.1.30
context=from-internal
allow=g729

User Details:sindos

type=user
secret=asco2000
host=192.168.1.30
context=from-internal
allow=g729

To Athens
Trunk Name: athens

username=athens
type=friend
trunk=yes
secret=asco3000
qualify=yes
host=192.168.3.30
context=from-internal
allow=g729

User Details:sindos

type=user
secret=asco2000
host=192.168.3.30
context=from-internal
allow=g729

Kavala Elastix

To Sindos
Trunk Name: sindos

Peer Details

username=sindos
type=friend
secret=asco2000
qualify=yes
host=192.168.2.30
context=from-internal
trunk=yes
allow=g729

User Details:kavala

type=user
secret=asco
host=192.168.2.30
context=from-internal
allow=g729

To Athens
Trunk Name: athens

username=athens
type=friend
secret=asco3000
qualify=yes
host=192.168.3.30
context=from-internal
trunk=yes
allow=g729

User Details:kavala

type=user
secret=asco
host=192.168.3.30
context=from-internal
allow=g729

Athens Elastix

To Kavala
Trunk Name: kavala

Peer Details

username=kavala
type=friend
trunk=yes
secret=asco
qualify=yes
host=192.168.1.30
context=from-internal
allow=g729

User Details:athens

type=user
secret=asco3000
host=192.168.1.30
context=from-internal
allow=g729

To Sindos
Trunk Name: sindos

Peer Details

username=sindos
type=friend
trunk=yes
secret=asco2000
qualify=yes
host=192.168.2.30
context=from-internal
allow=g729

User Details:athens

type=user
secret=asco3000
host=192.168.2.30
context=from-internal
allow=g729

At last after 2 days trying deleting and creating trunks it worked with the following configuration!I assume some bug required restart after its deletion or creation of a trunk.

InterCompany Trunks

Sindos Elastix

To Kavala

Trunk Name: kavala
Peer Details

username=kavala
type=friend
trunk=yes
secret=asco
qualify=yes
host=192.168.1.30
context=from-internal
allow=g729

User Details:sindos

type=user
secret=asco
context=from-internal
allow=g729

To Athens

Trunk Name: athens
Peer Details

username=athens
type=friend
trunk=yes
secret=asco
qualify=yes
host=192.168.3.30
context=from-internal
allow=g729

User Details:sindos

type=user
secret=asco
context=from-internal
allow=g729

Kavala Elastix

To Sindos

Trunk Name: sindos
Peer Details

username=sindos
type=friend
secret=asco
qualify=yes
host=192.168.2.30
context=from-internal
trunk=yes
allow=g729

User Details:kavala

type=user
secret=asco
context=from-internal
allow=g729

To Athens

Trunk Name: athens
Peer Details

username=athens
type=friend
secret=asco
qualify=yes
host=192.168.3.30
context=from-internal
trunk=yes
allow=g729

User Details:kavala

type=user
secret=asco
context=from-internal
allow=g729

Athens Elastix

To Kavala

Trunk Name: kavala
Peer Details

username=kavala
type=friend
trunk=yes
secret=asco
qualify=yes
host=192.168.1.30
context=from-internal
allow=g729

User Details:athens

type=user
secret=asco
context=from-internal
allow=g729

To Sindos

Trunk Name: sindos
Peer Details

username=sindos
type=friend
trunk=yes
secret=asco
qualify=yes
host=192.168.2.30
context=from-internal
allow=g729

User Details:athens

type=user
secret=asco
context=from-internal
allow=g729

Thank you for your replies!!!