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Maximizing a single Obi200 for a Voice and a Fax line and Rotary phones

Started by markosjal, June 10, 2021, 04:44:20 AM

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I put together the attached for those interested in understanding how this would work.

By default it would give you a Fax line with TouchTone support and a voice line with rotary dial support.

It however can also give you more options (see attached) like multiple simultaneous calls.
Phat Phantom's phreaking phone phettish


Interesting. I use an Obi with a rotary phone using an Xlink which works well...


I guess you connect the xlink to the bluetooth option of the obi? Expensive solution
Phat Phantom's phreaking phone phettish


no not using bluetooth. Just plugged phone into xlink and xlink into obi. Had these separately on different phones and thought I would try using them together. I now have a rotary phone using google voice in a room with no wired connections.


This provides more details for original post. It is not identical the OP as it does not use the Fax line . To have the Obi phone port used for Fax you would need to configure Google Voice on SP2 for use with the Grandstream instead of SP1 as used here. Sp1 could then be used as a dedicated Fax with the Obi Port by configuring a different Google Voice account there..

This is NOT A HACK.

In my example you will see on the Obi200:

  • Google Voice configured on SP1 for Voice calling
  • SP2 Unconfigured (but could be used in Place of SP1 if I do not need SP1's Phone port, then could use the Obi Phone port for fax Machine or DTMF only line with different Google Voice Account..)
  • Incoming calls will ring to both Obi200 Phone Port and Port 1 of the Grandstream.
  • outbound calls can be made from Grandstream Port 1 or Obi200 Phone port
  • 2 Simultaneous inbound and/or outbound calls are possible in this configuration . One via Rotary or Touchtone Phone on Grandstream and another  via the Obi200 Port Touchtone only.

Just FYI my Grandstream was purchased at Goodwill for about 3 Dollars. It was locked to Vonage and I used a common hack to unlock it. It did require the connection of a serial cable but was easy.

Of course Obi and Grandstream MUST be connected to the same LAN connection with Internet.

Because I am Lazy and I have everything working right and do not want to undo it,  I am also including the configuration for NoMoRobo which is a cheat because I have to Tell NoMoRobo that I am using but it works. Set up your account at to use it.

This also takes advantage of GV911 by converting a dialed 911 number to the appropriate number. IT IS YOUR RESPONSIBILITY TO TEST IT!

This configuration uses Fixed IP addressing as neither the Grandstream nor the Obi200 is a registrar server. You will also not that registrations are DISABLED on both Grandstream and Obi200

This assumes you have reset the Obi200 or have a Factory fresh unit and that the basic set up for Google Voice working and configured with the ObiTalk portal, and that you have the default set-up working for GV911 (by way of the Obi200 phone port), and tested.


Configure Grandstream as follows:

Reset all settings first (default)

Set Fixed IP
In our example We will set the Grandstream to Change this as you need to for your network.

Be sure to set proper subnet mask, gateway IP , DNS Servers, etc.

Please also note that because we are using Port1 on the Grandstream and the default Local SIP Port setting, Our Local Sip Port for the Grandstream will be 5060 so any calls or SIP connections we make will be to (more on this later). If you use default settings with Grandstream Port 2 it would be because port 5061 pertains to the second Phone port.

If a setting is not mentioned leave at default setting

Grandstream FXS Port 1 settings:
Primary SIP Server:   
Failover SIP Server: 0
Outbound Proxy:
Backup Outbound Proxy:
Note that in the 5062 above this refers to the local SIP port of the Obi200. See the Obi configuration below for more info.

NAT Traversal: No

SIP User ID:100    
Authenticate ID:100
Authenticate Password:999

DNS Mode: Use Configured IP

SIP Registration:No
Unregister On Reboot:No
Outgoing Call without Registration:Yes 

Use Random SIP Port:No 
Use Random RTP Port:No     

Validate Incoming SIP Message: No
Check SIP User ID for incoming INVITE: No
Authenticate incoming INVITE: No
Authenticate server certificate domain: No 
Authenticate server certificate chain:No
Allow Incoming SIP Messages from SIP Proxy Only: No 
Use Privacy Header:      Default       No       Yes
Use P-Preferred-Identity Header:Default
Use P-Access-Network-Info Header: Yes
Use P-Emergency-Info Header:Yes
Use P-Asserted-Identity Header:No

Preferred DTMF method
Priority 1:RFC2833
Priority 2:RFC2833
Priority 3:RFC2833
Disable DTMF Negotiation:No (negotiate with peer)

Dial Plan: { <911=4242798234>|<922=4242798235> | 1[2-9]xxxxxxxxx | [2-9]xxxxxxxxx | <=503>[2-9]xxxxxxT | x+ | *x+ | *xx*x+ }

Please note, the above dial plan uses GV911 and turns dialing 911 into the PSTN number 4242798234 which is the official 911 POTS equivalent once you are registered for GV911 . If you are NOt registered it will not work. 922 goes to a test number. 503 is my local area code for 7 digit dialing.Change 503 to your area code.

Configure Obi200 

You either need to make these change entirely in Obi portal or Entirely in the device itself. Because you probably configured Google Voice in the Obitalk portal you should use expert mode there to do this as well.

Do not forget you must disable the check boxes on the right of an item before setting it manually

We will use sp3 and ITSP Profile C for this configuration example to communicate with the Grandstream.
We will use sp1 and ITSP Profile A for the configuration example to communicate with Google Voice

We will first set a fixed IP address. In this example we use

You also need to set a valid Gateway IP, DNS Servers, and Subnet mask.

Because we are using SP3 on the Obi200 the default local SIP port is 5062 when we send calls to or from Obi. We use this more in the Grandstream configuration than here, so the Grandstream can reach the Obi.

Modify the Google Voice Profile on sp1  (sp2 if using sp1 for Fax)
Voice services > sp1 service
X_InboundCallRoute: {ph,sp3(100@;ui=$1),sp4(;ui=$1)}
(this allows the incoming calls to fork to The Obi phone port, Grandstream Phone Port and NoMoRobo where whoever answers first gets the call.)

On the page ITSP Profile C > General
Name: Grandstream

Name: Grandstream (again)

On the page ITSP Profile C > SIP
ProxyServerPort: 5060 (if using Port 1 on Grandstream with default local port on grandstream.)
OutboundProxyPort: 5060

X_SpoofCallerID: X (checked)
X_DiscoverPublicAddress: (unchecked) all boxes to right unchecked as well.

Voice Services > SP3 Service
X_ServProvProfile: C
X_InboundCallRoute: sp1 (set to sp2 if using Obi200 phone port for Fax)
X_RegisterEnable:  (unchecked)

AuthPassword: 999
URI: 100@ (note if grandstream were using Port 2 with default settings this would be 100@

Voice services > SP4 (config for NoMoRobo)

X_ServProvProfile D

X_RegisterEnable (unchecked)

Auth Username <1+your Phone number>

Service Providers > ITSP Profile D SIP



Enjoy you new FREE Rotary phone compatible phone service as all you pay is $12.00 per year for GV911

Phat Phantom's phreaking phone phettish


I tried doing this setup but it doenst work, I am using a Grandstream ht802 that I bought off Amazon.  Also how to set fixed IP address using the obihai?


RotaryPhoneLover2000 , do you have any idea where it has gone wrong? Are you able to get a dial tone out of the Grandstream?

You MUST set Fixed IP on the Obi200 or you will probably have issues. I do not believe you can do that in Obitalk portal. You must log in to Obi at the IP address of the Obi.

PM Me if you need some help. Sorry for the delay I have not been here for a month or so.
Phat Phantom's phreaking phone phettish


I see there is an error in this configuration post the Grandstream Line2 uses the default SIP Port of 5062 not 5061. I am unable to edit it
Phat Phantom's phreaking phone phettish