...

When call is made with JavaScript API, an additional parameters can be passed to control bandwith via SDP, for exampleoutgoing calls (to INVITE request)

var sdpAttributes = ["b=AS:3000","b=TIAS:2500000","b=RS:1000","b=RR:3000"];
var outCall = session.createCall({
        sipSDP: sdpAttributes,
        ...
    });

Those parameters will be added to SDP after connection information ("c=IN IP4 <WCS IP>") and before time description ("t=0 0") to INVITE request (for outgoing calls) and 200 OK response (for incoming calls):and incoming calls (to 200 OK response)

v=0
o=Flashphoner 0 1541068898263 IN IP4 192.168.1.5
s=Flashphoner/1.0
c=IN IP4 192.168.1.5
        var sdpAttributes = ["b=AS:3000
","b=TIAS:2500000
","b=RS:1000
","b=RR:3000
t=0 0
"];
		inCall.answer({
            sipSDP: sdpAttributes,
            ...
        });

Those parameters will be added to SDP after connection information ("c=IN IP4 <WCS IP>") and before time description ("t=0 0"):

v=0
o=Flashphoner 0 1541068898263 IN IP4 192.168.1.5
s=Flashphoner/1.0
c=IN IP4 192.168.1.5
b=AS:3000
b=TIAS:2500000
b=RS:1000
b=RR:3000
t=0 0
m=audio

Known issues

1. It's impossible to make a SIP call if 'SIP Login' and 'SIP Authentification name' fields are incorrect

...

var outCall = session.createCall({
    callee: $("#callee").val(),
    visibleName: $("#sipLogin").val()val(),
    localVideoDisplay: localDisplay,
    remoteVideoDisplay: remoteDisplay,
    constraints: constraints,
    receiveAudio: true,
    localVideoDisplayreceiveVideo: localDisplayfalse,
    remoteVideoDisplaystripCodecs: remoteDisplay"silk,g722"
     constraints: constraints,
    receiveAudio: true,
    receiveVideo: false,
    stripCodecs: "silk,g722"
    ...
});

outCall.call();

3. Microphone swithing does not work in Safari browser.

Symptoms: microphone does not switch using switchMic() WCS WebSDK method.

Solution: use another browser, because Safari always uses sound input microphone, that is chosen in system sound menu (hold down the option (alt) button and click on the sound icon in the menu bar). When microphone is chosen in sound menu, Mac reboot is required.

...

...
});

outCall.call();

or with server setting

codecs_exclude_sip=g722,mpeg4-generic,flv,mpv

3. Microphone swithing does not work in Safari browser.

Symptoms: microphone does not switch using switchMic() WCS WebSDK method.

Solution: use another browser, because Safari always uses sound input microphone, that is chosen in system sound menu (hold down the option (alt) button and click on the sound icon in the menu bar). When microphone is chosen in sound menu, Mac reboot is required.

If Logitech USB camers microphone does not work (when it is chosen in sound menu), format / sample rate changing in Audio MIDI Setup and rebooting can help.

4. Outgoing video SIP call cannot be established if INVITE SDP size exceeds MTU

Symptoms: SIP server return 408 Reques timeout when trying to establish video SIP call, audio calls can be established successfully through the same server.

Solution: reduce the number of codecs in the INVITE SDP so that the SDP fit into the packet size defined by MTU (usually 1500 bytes) using the following settings

codecs_exclude_sip=mpeg4-generic,flv,mpv,opus,ulaw,h264,g722,g729
allow_outside_codecs=false

Only codecs supported by both sides of the call should be left, in this case it is VP8 and PCMA (alaw).