Вот лог из отладчика
DX:MP3 Writer initialized
DX:MP3 Encoder initialized
DX:FFDShow not present
Missing translated word for: cmn.none (None)
Missing translated word for: dlgconn.ck.useprov (Perform provisioning from following URL

Missing translated word for: dlgconn.lb.accname (Account name

Missing translated word for: dlgconn.lb.callerid (Caller ID

Missing translated word for: dlgadv.lb.vcodecs (Video codecs)
Missing translated word for: dlgadv.lb.vformats (Video formats)
Missing translated word for: dlgprf.ck.ckupdates (Automatically check for updates)
Missing translated word for: dlgprf.lb.lport (Local SIP port

Missing translated word for: dlgprf.lb.rtpport (RTP ports

Missing translated word for: dlgprf.ck.anyloc (Any)
Missing translated word for: dlgprf.vidframe (Video)
Missing translated word for: dlgprf.viddesc (Video source

Missing translated word for: dlgprf.vidcfg (Configure)
Missing translated word for: dlgprf.vidallow (Allow video calls)
Missing translated word for: dlgprf.vidstartonest (Start sending video when call is established)
Missing translated word for: dlgprf.vidnosendonhid (Do not send video when phone is inactive or hidden)
Missing translated word for: dlgprf.netframe (General network settings)
Missing translated word for: dlgprf.echocancel (Echo cancellation)
Missing translated word for: dlgprf.noisered (Microphone noise reduction)
Missing translated word for: dlgacc.caption (Accounts)
Missing translated word for: dlgacc.accframe (Accounts)
Missing translated word for: dlgacc.accdesc (Manage SIP accounts)
Missing translated word for: dlgacc.btnew (New)
Missing translated word for: dlgacc.btedit (Edit)
Missing translated word for: dlgacc.btdel (Remove)
Missing translated word for: dlgacc.btskeys (Soft keys)
Missing translated word for: dlgacc.btok (OK)
Missing translated word for: dlgacc.btcancel (Cancel)
Missing translated word for: dlgacc.colactive (Active)
Missing translated word for: dlgacc.colname (Name)
Missing translated word for: dlgacc.coldomain (Domain)
Missing translated word for: dlgacc.colcallid (Caller ID)
Missing translated word for: dlgselacc.caption (Account selection)
Missing translated word for: dlgselacc.desc (Select desired account)
Missing translated word for: dlgselacc.btok (OK)
Missing translated word for: dlgselacc.btcancel (Cancel)
Missing translated word for: dlgskey.caption (Softkeys configuration)
Missing translated word for: dlgskey.btok (OK)
Missing translated word for: dlgskey.btcancel (Cancel)
Missing translated word for: dlgskey.colkey (Key)
Missing translated word for: dlgskey.coltype (Type)
Missing translated word for: dlgskey.coluserid (User ID)
Missing translated word for: dlgskey.collabel (Label)
Missing translated word for: dlgskey.colacc (Account)
Missing translated word for: dlgskey.typesdial (Speed dial)
Missing translated word for: dlgskey.typeblfxfer (BLF/XFer)
Missing translated word for: dlgskey.accany (Any)
Missing translated word for: dlgskey.accnotset (Not set)
Missing translated word for: dlgskey.lbbank (Show softkeys for

Missing translated word for: dlgskey.bank (Softkeys bank)
Missing translated word for: dlgskey.allskeys (All softkeys)
Missing translated word for: dlgskey.btup (Move up)
Missing translated word for: dlgskey.btdown (Move down)
Missing translated word for: dlgskey.btclear (Clear all)
Missing translated word for: dlgskey.btload (Load)
Missing translated word for: dlgskey.btsave (Save)
Missing translated word for: dlgskey.lbpresets (Softkeys presets

Missing translated word for: dlgskey.blffileext (3CXPhone BLF config files)
Missing translated word for: dlgskey.wrongpreset (Invalid 3CXPhone BLF configuration file!)
Missing translated word for: dlgskeycfg.caption (Softkey configuration)
Missing translated word for: dlgrec.ck.recasmp3 (Record as MP3 stereo)
Missing translated word for: dlgrec.lbaccount (Account

Missing translated word for: dlgch.calltype (Type of calls

Missing translated word for: dlgch.allaccounts (All accounts)
Missing translated word for: stat.declined (Declined)
Missing translated word for: stat.provisioning (HTTP Provisioning...)
Missing translated word for: stat.noaccounts (No active accounts configured)
Missing translated word for: stat.setaccounts (Set accounts)
Missing translated word for: vid.fullscreen (Full screen mode)
Missing translated word for: vid.nowebcam (No webcam set)
Missing translated word for: vid.mod.live (LIVE)
Missing translated word for: vid.mod.paused (PAUSED)
Missing translated word for: vid.mod.pausedrec (PAUSED-REC)
Missing translated word for: vid.mod.sending (SENDING)
Missing translated word for: vid.mod.sendingrec (SENDING-REC)
Missing translated word for: vid.mod.recording (RECORDING)
Missing translated word for: vid.mod.standby (STANDBY)
Missing translated word for: vid.mod.standbyrec (STANDBY-REC)
Missing translated word for: vid.mod.hold (ON HOLD)
Missing translated word for: vid.mod.holdrec (ON HOLD-REC)
Missing translated word for: answp.online (on line)
Missing translated word for: dlgvm.caption (Voicemail number)
Missing translated word for: dlgvm.desc (Configure the Voicemail extension number to be used by this account. This can be changed later from account's Advanced settings.)
Missing translated word for: dlgvm.btok (OK)
Missing translated word for: dlgvm.btcancel (Cancel)
Missing translated word for: dlgepn.caption (Edit phone number)
Attempting to connect 192.168.1.20
Phone got as local port 64312
Jabra not connected
RTP engine OK
SIP engine OK
Sound mic device OK [{2987B6A0-3FD5-4D99-8E0C-56C41BBB6447}]
Sound ring device OK [{C8CEA7DA-86FA-43F6-99A0-9A733C9ECE56}]
Sound speaker device OK [{004F6FE9-F818-4176-B69B-99493ADD26E9}]
Phone is now connected
Video calls not allowed
Насчет смены протокола, то этот способ не помогает.