Hi Diana
You are free to request a paper-based assessment, but they are unlikely to grant one without a doctor's letter confirming that it would cause you 'overwhelming psychological distress' to have a telephone assessment. Be warned even then the DWP and/or the assessment services sometimes ignore such requests. I've only ever known two people get paper-based without a medical professional's back up.
If you have a paper-based assessment are you chances improved or disadvantaged? it's almost impossible to say in the current circumstances. Paper-based assessments are great in there is no stress or intrusive questions from an assessor, however, they have a disadvantage in that there is no opportunity to clarify any questions the assessor may have or say something you have forgotten on the form.
BIS
Nothing on this board constitutes legal advice - always consult a professional about specific problems