Good Sip client for windows?

Question

SIP

Looking for a sip client for machines running xp,7. Requirements for the client - sane appearance, stability, the ability to make transfers (transfers) of calls, free of charge, ease of installation.
habrahabr.ru/qa/12190/ read.
en.wikipedia.org/wiki/Comparison_of_VoIP_software - I saw
ZoiperFree closest to the ideal, but the free version does not want to transfer, x-lite 5 is incredibly buggy and infuriates with ads, and older versions where beauty has not yet been heaped up do not always work. From the tried clients it is already beginning to feel sick, but the ideal has not been found.
Paid things are also considered in case of lack of fish. Thank you.
UPD1:The most sane of the paid ones so far are Bria ($49.95) and the same ZoiperBiz (€29.45), but Bria has a not very pleasant bug: if there is a long history of calls, miracles begin. Constantly cleaning history is not good. Yes, I don't want to pay extra money.
UPD2: Setup problems disappeared in 10 minutes with autoit, so in this situation they are no longer critical. in a month I will sign here in more detail why and on what they decided to stop.
UPD3: Zoiper proved to be good, but rather unstable in some situations (it likes to hang when connecting / disconnecting the headset, for example). It's a pity.
UPD4:Zoiper, unfortunately, showed a high craving for sorties. It’s good that he doesn’t do it during calls, it’s bad that he does it all the time. X-lite 3 generates a license during installation, which immediately expires (I didn’t look for a solution / didn’t find it), X-lite 4 works, X-lite 5 works similarly but a little slower. 3CXPhone works ok, including not on Windows . Codecs do not bother at all. those that are there allow you to hear everything normally. I personally liked Phonerlite and worked, the “testers” don’t like the interface for some reason. YateClient has not been tested. So far, we decided not to twitch and use X-lite 5 / Bria, despite the presence of lighter and more convenient softins, but mainly due to the fact that bugs have already traveled around them and there are practically no new ones.
UPD5:X-lite 4 after a month of use stopped running, X-lite 5 Updated to 4.5.

Answer 1

And to add one of the free open source codes to the needs of the company?
sipek/pjproject on .Net are done.

Answer 2

See also 3CXPhone. Free. There is a transfer. Of the minuses - few codecs.

Answer 3

habrahabr.ru/company/onlinepbx/blog/165799/

Answer 4

I have either X-Lite 3 or X-Lite 5 on all machines and did not notice its glitches. What exactly is manifested?
The shuttle service to ZoiperFree also worked.

Answer 5

I really liked YateClient yateclient.yate.ro/
OpenSource written in C++ Qt4.
The interface is pleasant, minimalistic. Works on Linux, Windows, MacOS X.
Did not use it in combat conditions.