Here's my version to be adapted as required:
Mini PBX – Two OBi ATAs With One PSTN Line
I'm going to use these values in my example:
OBi100 sp1 ip address 192.168.1.10 UserAgentPort 5070
OBi110 sp1 ip address 192.168.1.11 UserAgentPort 5080
OBi100 (201):
Physical Interfaces > PHONE Port > PrimaryLine: SP1 Service
Speed dial slot 10: sp1(202@192.168.1.11:5080)
Service Providers -> ITSP Profile A -> SIP -> ProxyServer : 127.0.0.1
Service Providers -> ITSP Profile A -> SIP -> ProxyServerPort : 5060
Service Providers -> ITSP Profile A -> SIP -> OutboundProxy : 192.168.1.11
Service Providers -> ITSP Profile A -> SIP -> OutboundProxyPort: 5080
Service Providers -> ITSP Profile A -> SIP -> X_SpoofCallerID : checked
The following DigitMap needs to be optimised for whatever numbers are being dialled out via PSTN. This might be typical:
Service Providers > ITSP Profile A > General > DigitMap:
(1xxxxxxxxxx|[2-9]xxxxxxxxx|[2-9]xxxxxxS4|011xx.|xx.)
Voice Services -> SP1 Service -> Enable : (checked)
Voice Services -> SP1 Service -> AuthUserName : 1234
Voice Services -> SP1 Service -> X_RegisterEnable : (unchecked)
Voice Services -> SP1 Service -> X_ServProvProfile : A
Voice Services -> SP1 Service -> X_UserAgentPort : 5070
Voice Services -> SP1 Service -> CallerIDName : distant
Voice Services -> SP1 Service -> MaxSessions : 4
Voice Services -> SP1 Service -> X_InboundCallRoute:
{>(201):ph}
OBi110 (202):
Physical Interfaces > PHONE Port > PrimaryLine: PSTN
Speed dial slot 11: sp1(201@192.168.1.10:5070)
Service Providers -> ITSP Profile A -> SIP -> ProxyServer : 127.0.0.1
Service Providers -> ITSP Profile A -> SIP -> ProxyServerPort : 5060
Service Providers -> ITSP Profile A -> SIP -> X_SpoofCallerID : checked
Voice Services -> SP1 Service -> Enable : (checked)
Voice Services -> SP1 Service -> AuthUserName : 5678
Voice Services -> SP1 Service -> X_RegisterEnable : (unchecked)
Voice Services -> SP1 Service -> X_ServProvProfile : A
Voice Services -> SP1 Service -> X_UserAgentPort : 5080
Voice Services -> SP1 Service -> CallerIDName : home
Voice Services -> SP1 Service -> MaxSessions : 4
Voice Services -> SP1 Service -> X_InboundCallRoute:
{1234>(202):ph},{1234>(xx.):li}
Physical Interfaces -> LINE Port -> DigitMap (typical) :
(1xxxxxxxxxx|[2-9]xxxxxxxxx|[2-9]xxxxxxS4|011xx.|xx.)
Physical Interfaces -> LINE Port -> InboundCallRoute
{ph,sp1(201@192.168.1.10:5070)}
I have not tested this exact config, but it's patched together using parts that work from other configs. It should work like so:
Either OBi should be able to dial out using normal PSTN numbers. Both use the PSTN line connected to the OBi110 (202).
An incoming PSTN call will ring the phones attached to both OBi's. First to answer takes the call.
OBi100 (201) dials 10# to call OBi110 (202).
OBi110 (202) dials 11# to call OBi100 (201).
Edit: Obi names changed to numbers for easier call routing.