about VCXO need help

This may help:
http://www.eta.chalmers.se/~pgp/vcxo/vcxo.html

Hello ,Vfone, Do you know how to calculate the load capacitance of the vcxo ?

Load capacitance is the capacitance needed to be placed in series with the crystal to bring the frequency within the calibration tolerance.

In the document below you can find the equations of load capacitance, how to keep the ppm variation in the required range:
http://www.crystek.com/appnotes/VCXOarticle.pdf

Vfone
According to the description of article,

"It's important to note here that there's no difference between a series
and a parallel crystal, only where it is calibrated by the manufacturer"

Who is the manufacturer here ? Crystal manufacturer or
product manufacturer (ex: cell phone) ?

Thanks a lot.