  In this paper we report that carrier-phase two-way satellite time and
frequency transfer (TWSTFT) was successfully demonstrated over a very long
baseline of 9,000 km, established between the National Institute of Information
and Communications Technology (NICT) and the Physikalisch-Technische
Bundesanstalt (PTB). We verified that the carrier-phase TWSTFT (TWCP) result
agreed with those obtained by conventional TWSTFT and GPS carrier-phase (GPSCP)
techniques. Moreover, a much improved short-term instability for frequency
transfer of $2\times10^{-13}$ at 1 s was achieved, which is at the same level
as previously confirmed over a shorter baseline within Japan. The precision
achieved was so high that the effects of ionospheric delay became significant
which are ignored in conventional TWSTFT even over a long link. We compensated
for these effects using ionospheric delays computed from regional vertical
total electron content maps. The agreement between the TWCP and GPSCP results
was improved because of this compensation.
