Cannot set authentication tls for sipe account (pidgin works fine though)

[lyncuser]

In pidgin to connect to the lync server of my company I need to adjust the useragent to CCAPI/4.0.7577.0 OC/4.0.7577.0 and the authentication scheme to tls-dsk. This works with pidgin.

I try to do the same with bitlbee however I cannot change the authentication scheme from ntlm to tls, so the connection always fails with,

<user> acc 1 on <root> sipe - Logging in: Connecting <root> sipe - Login error: Incompatible authentication scheme chosen <root> sipe - Logging in: Signing off..

<user> acc 1 set <root> authentication = `ntlm' <root> auto_connect = `true' <root> auto_reconnect = `true' <root> away is empty <root> display_name is empty <root> email = `' <root> email_login = `' <root> email_password = `' <root> email_url = `' <root> groupchat_user = `' <root> nick_format is empty <root> nick_source = `handle' <root> password = `' (hidden) <root> server = `' <root> sso = `true' <root> status is empty <root> tag = `sipe' <root> transport = `auto' <root> useragent = `CCAPI/4.0.7577.0 OC/4.0.7577.0' <root> username = `'

Here I try to switch to 'tls' but the bitlbee server on localhost answers always with 'ntlm'

<user> acc 1 set authentication = 'tls' <root> authentication = `ntlm'

$ dpkg -l | egrep "bitlbee|sipe" ii bitlbee-common 3.2.1+otr4+20140214+devel+1011-1 An IRC to other chat networks gateway (common files/docs) ii pidgin-sipe 1.13.1-2 Pidgin protocol plugin to connect to MS Office Communicator