My home fibre bradband ISP provides me with a Huawei HG8240 optical network terminal. This has one ethernet port and one phone port. The phone port is active, but unused at the moment.

The ethernet port is connected with a linux box, acting as a router, dns server, dhcp server and many more things. The linux box has two ethernet interfaces, one connected to the Huawei device facing the wan, the other connected to a switch and servicing various access points and cabled stations in the house.

My goal: I would like to route phone calls originated from wireless devices connected to the lan (e.g. tablets and smartphones) via the phone line provided by the ISP.

I reckon I need:

  • a voip server running on the linux box
  • a voip client compatible with the server running on the tablets and smartphones
  • some physical device which connects the linux machine to the Huawei telephone port, compatible with the voip server. Does anybody has suggestions about open source packages and hardware devices which may allow to set this up?

Regarding the physical device, what is the name of the device I am looking for? I tried to search for "usb to voip", "usb to sip", "connect a pc to a phone line", but all devices I could find seem oriented to replace the phone line with various voip service, which is not what I need.


VoIP server: Asterisk or FreeSWITCH

VoIP client: CSipSimple for Android, based on PJSIP

SIP adapter: try searching SIP to RJ11 on eBay

Reference: my own experience

  • 3
    Be careful if you look for a SIP to RJ11 device on EBAY. Most will not do what you want. You need to make sure it is an FXO device rather then an FXS device. (Some hardware has both ports). A better ebay search might be "fxo ata" – davidgo Nov 7 '17 at 8:57
  • Thanks for the kind reminder... I used to work with SIP softphones but not SIP to PSTN hardware switches (which we outsourced to various vendors) – Chang Qian Nov 7 '17 at 9:17
  • Thanks. Would you also recommend any client compatible with asterisk for iPhone? PocketOperator may be? – Fabio Nov 8 '17 at 1:51

The best way would be to use Asterisk or Freeswitch to act as your router, and try and co-opt the settings used by your ISP into Asterisk. (This is very often technically possible, but often ISP's don't want to help, and even downright lie about it).

If its not possible, you can get an FXO device which will allow you to plug the analog line from your ISP into your equipment. A cheap way of doing this is to get an X100P (or clone) card for Asterisk. Be warned that this solution has substantial drawbacks, including possible echo problems - and not all X100P clones are made equal. (You can also get a device like an SPA2102 or equivalent which does the same thing as an Asterisk X100P card, but connects over Ethernet as a SIP line, and might - or might not - give you fewer issues).

  • are you suggesting to compeletely bypass the ISP optical terminal, also for Ethernet? But for that I would still need some sort of adaptor to connect the fibre with the PC. – Fabio Nov 7 '17 at 14:50
  • Looking into your HG8240 makes me say ' I'm not sure". I'm I'm speculating you may be able to reconfigure it/use it to pass all traffic to your router, and then split the VOIP traffic off it (its delivered to the router on a separate VLAN). Without spending a lot of time with your setup I can only speculate and guess that its possible to pass the traffic on the VOIP VLAN through to your router which could then terminate it and provide it to Asterisk – davidgo Nov 7 '17 at 17:57
  • Very interesting. Browsed through the web configuration interface of the HG8240H. It seems there is no pass-through option for the voice. I will give a try at the second suggestion, using. SPA2012. If I understand, I plug that in the voice port and plug the Ethernet port into a switch connected to the lan, which will assign to the SPA2012 a local IP. Then there will be a way to tell Asterisk to use that IP to forward calls outside? – Fabio Nov 8 '17 at 1:48
  • Yes, you can I structure asterisk to dial a number on an fxo port. – davidgo Nov 8 '17 at 1:52
  • Reading specs of various devices, I found the SPA2102 has 2 FXS port. If I understand correctly, I need an FXO port. Hence SPA3102 (discontinued by the vendor) or HT503 might be the right ones to use, as both have an FXO port. – Fabio Nov 9 '17 at 8:19

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