How to set up the Obihai OBi110 as a PSTN gateway

The OBi 110 provides an FXO port to connect to an analogue telephone line (PSTN). Once it is connected, you can use the OBi110 as a SIP gateway to that telephone line. It provides inbound and outbound calling functionality.

After changing each page, you should click the Submit button at the bottom of the page.

First, configure the OBi110 with a static IP address in System Management -> Network Settings:

OBi110 Network Config

OBi110 Network Config

Now configure the ITSP profile. Give the profile a name in Service Providers -> ITSP Profile A -> General:

OBi 110 ITSP Profile Settings

OBi 110 ITSP Profile Settings

Configure the SIP settings for the profile in Service Providers -> ITSP Profile A -> SIP. There’s a lot here but you should only need to configure the IP/hostname of your SIP provider and enable caller ID spoofing (this sends the caller ID received from the PSTN to the SIP endpoint):

OBi 110 ITSP Profile SIP Settings

OBi 110 ITSP Profile SIP Settings

Configure the SIP Provider service in Voice Services -> SP1 Service. You will provide your SIP username and password as well as making inbound calls to the OBi110 route to the “Line” (PSTN) port:

OBi110 SP1 Service Settings

OBi110 SP1 Service Settings

Now you should disable the junk, if you don’t need it. Go into each of the following and untick the “Enable” box:

Voice Services -> SP2 Service
Voice Services -> OBiTALK Service
Voice Services -> Auto Attendant

You now need to configure the LINE port to call a given number over the SP1 SIP trunk when it receives an inbound call. I have picked 22222 as that number – you can choose anything that the PBX accepts. Do this under Physical Interfaces -> LINE Port.

OBi110 LINE Port Settings

OBi110 LINE Port Settings

If, like me, you want to configure the phone attached to the PHONE port to dial over SIP rather than the PSTN, you’ll need to change PrimaryLine under Physical Interfaces -> PHONE Port:

OBi110 PHONE Port Settings

OBi110 PHONE Port Settings

You can now reboot the OBi100 by clicking the Reboot button in the top right.

The OBi110 will now register (i.e. send a SIP “REGISTER”) to the host configured in Service Providers -> ITSP Profile A -> SIP. If you see it register, you’re good to go. Calls into the OBi110 from the PSTN will route to the number that you configured in Physical Interfaces -> LINE Port. Calls that you send over SIP to the OBi110 will be routed out onto the PSTN.

If you are in the UK, you should read my other post about configuring the PHONE/LINE (FXS/FXO) settings to work in the UK.

How to configure the Obihai OBi110 for the United Kingdom PSTN

The OBi110, as with most ATAs, comes configured for the US. For those of us on the other side of the pond, in the UK, it’s always a challenge to get ATAs to work. Here are the required settings for the OBi110 in the UK. They’ve been acquired collectively from a few sources but have been proven to work for inbound and outbound calls. Anything not mentioned should be left with the Default checkbox ticked.

Physical Interfaces -> PHONE Port:

  • Impedance: 370+(620||310 nF)
  • CallerIDMethod: FSK(V.23)
  • CallerIDTrigger: After Polarity Reversal
  • HookFlashTimeMin: 150

Physical Interfaces -> LINE Port:

  • RingDelay: 0 (don’t worry, caller ID still works if it’s enabled on your line)
  • RingProfile: B (the default B profile seems to work well in the UK)
  • CPCTimeThreshold: 90
  • DetectPolarityReversal: Unticked
  • SilenceTimeThreshold: 30
  • DisconnectTonePattern: 400-30;2
  • ACImpedance: 370+(620||310 nF)
  • OnHookSpeed: 3 ms (ETSI)
  • CurrentLimitingEnable: Ticked
  • CallerIDDetectMethod: FSK(V.23)
  • RingFrequencyMin: 10
  • RingThreshold: 13.50-16.50
  • RingIndicationDelayTime: 0
  • RingTimeout: 128

Tone Settings -> Tone Profile A:

  • Dial Tone: 350-18,440-18;20
  • Ringback Tone: 400-18,450-18;20;(.4+.2,.4+2)
  • Busy Tone: 400-18;20;(.375+.375)
  • Reorder Tone: 400-18;20