NekoIMS is a portable IMS client built on top of BareSIP in C++11

./start.sh

Builds NekoIMS if needed, starts the SIM server for the attached SIM (PC/SC reader or ModemManager modem, --sim pcsc|mm to choose), generates the config from the SIM with tools/mkconfig.py (a carrier bundle if there is one for the SIM, else the 3GPP discovery names, provided the ePDG resolves; it asks for the phone number if the SIM doesn't carry it), dials the ePDG with the static neko-strongswan build and runs NekoIMS inside the tunnel's ims netns, using the P-CSCF the ePDG assigned. It asks for sudo after building. ./start.sh --help lists the options; arguments after -- go to nekoims.

./start.sh --qmi-ims [--apn ims] [--apn_data vzwinternet]

Instead of the ePDG, registers over the modem's own IMS PDN.

The SIM server needs the AT port to itself, so stop ModemManager first sudo systemctl stop ModemManager.

This option refuses to run while it uses the port. Needs libqmi's GObject bindings and pyserial.

powershell -ExecutionPolicy Bypass -File start.ps1

The same steps as start.sh: builds NekoIMS (Visual Studio with the C++ workload, Ninja and Git needed), re-runs itself as Administrator, starts simcard-server/server.py on http://127.0.0.1:8888 for the PC/SC reader (or uses a SIM server that already answers there, or wherever -SimServer points, e.g. -SimServer http://host:5309 for one on another machine), runs mkconfig, dials the ePDG and runs NekoIMS. Get-Help .\start.ps1 or the top of the file lists the options; arguments after -- go to nekoims. Python 3 with pyscard is needed for the SIM server and mkconfig.

Windows on ARM uses the x86_64 strongSwan build due to what seems to be a compiler but on llvm arm64 windows targets with varargs. NekoIMS itself builds natively. sec_agree (IMS IPsec, needed by AT&T) is not implemented on Windows yet.

• libcurl
• BareSIP
• vo-amrwbenc
• opencore-amr
• https://github.com/nlohmann/json
• (optional) pcsclite for simcard-server

cmake -S . -B build -G Ninja -DCMAKE_BUILD_TYPE=Release
cmake --build build -j$(nproc)

On Windows, run the same commands from a Visual Studio developer prompt (MSVC, x64 or ARM64). Git must be on PATH. Audio uses WASAPI (audio_device defaults to default) instead of ALSA, and AMR is compiled in tree since autotools isn't available.

Copy nekoims.example.json to nekoims.json and edit

• IMEI
• Domain (ims.mnc.mcc.pub.3gppnetwork.org) or vzwims.com for Verizon
• pcscf (from VPN or whatever value is relevant to your ims bearer if directly attached)
• msisdn (to your phone number)

baresip's remote control interfaces are both off by default, but can be enabled as follows

• "ctrl_tcp": true: JSON commands and events over netstrings on ctrl_tcp_listen (default 127.0.0.1:4444), e.g. {"command":"dial","params":"+15551234567"}
• "httpd": true: menu commands over HTTP on http_listen (default 127.0.0.1:8000), e.g. curl 'http://127.0.0.1:8000/?d+15551234567'

Neither one supports auth, so anyone who can connect can place calls. Keep them on localhost.

SMS over IMS in both directions, in 3GPP (application/vnd.3gpp.sms) or 3GPP2 (application/vnd.3gpp2.sms, which Verizon uses) format. Received SMS are acknowledged to the network and handed to baresip as text/plain messages (console, ctrl_tcp message events), and in B2BUA mode also relayed to the external UA.

"sms": { "rx": "plain", "tx": "plain", "format": "auto", "smsc": "" }

• rx: what SIP clients receive. plain is the decoded text; SMS without a text form (WAP push, binary data) fall back to binary_b64, the original bytes as a data URI: data:application/vnd.3gpp2.sms;base64,...
• tx: what SIP clients send. plain text is encoded into an SMS here; binary_b64 expects the same data URI form. A MESSAGE that is already application/vnd.3gpp(2).sms is sent as is either way
• format: auto sends in the format SMS were last received in (3GPP until one arrives), or force 3gpp / 3gpp2
• smsc: service centre URI or number to send to. By default, wherever the last received SMS came from
• off for rx or tx disables that direction

You can also send with the sms command, from the console, ctrl_tcp ({"command":"sms","params":"+15551234567 hi"}) or httpd, or in B2BUA mode with a SIP MESSAGE from the external UA to <number>@<NekoIMS>. The network's verdict arrives as an SMS of its own: with rx plain it's reported as an sms module event (sent / failed), with binary_b64 it's delivered as is. Only single-part messages can be sent for now (160 characters, or 70 outside the GSM/ASCII character set).

Unless contact_features is set explicitly, +g.3gpp.smsip is added to the registration string so the network delivers the SMS over IMS. If you set contact_features, add it yourself.

With "b2bua": {"enabled": true, ...} NekoIMS runs headless and bridges calls to an external SIP UA (desk phone, softphone, PBX trunk) instead of the sound card. This is useful for peering with asterisk or using gnome-calls or another softphone. Note that this mode is likely filled with bugs.

• username / password: digest credentials the external UA uses for its REGISTER and INVITEs (no password means no authentication, only do that on a trusted network)
• target: optional fixed URI for incoming IMS calls, used when no UA is registered, e.g. sip:100@192.168.1.20:5060
• listen: optional address (no port, sip_port is used) to serve the external UA on, e.g. 127.0.0.2 or 192.168.1.10. NekoIMS then binds SIP only there and on the IMS side: the interface addresses if set, else just the address the P-CSCF is reached from. Requests for the external UA's account arriving anywhere else are refused. Without listen, NekoIMS binds every address and interface is ignored in this mode
• netns (Linux): network namespace listen is in, as a path (/proc/1/ns/net for the host's) or a name from /run/netns.
• audio_codecs: codecs offered to the external UA (default PCMU/8000,PCMA/8000; AMR-WB/16000, AMR/8000 and G722/16000 also available)

On Windows, set listen to the LAN address (or 127.0.0.1 for a softphone on the same machine). Network namespaces are not used on windows, you do not need to set netns (nor is that option supported).