The Old Sogdian script is not yet in Unicode. The script has a tentative allocation at U+10F00..U+10F2F in the  Roadmap to the SMP for the Unicode Standard.

A number of proposals for its inclusion has been submitted to the Unicode Technical Committee and WG2:

2015-11-03 Preliminary Proposal to Encode the Old Sogdian Script in Unicode — Anshuman Pandey ( L2/15-089)

UTC #146 Minutes ( L2/16-004) (See D.4 for decision and action items)

2016-12-31 Proposal to encode the Old Sogdian script in Unicode — Anshuman Pandey ( L2/16-312)

Recommendations to UTC #150 January 2017 on Script Proposals ( L2/17-037) (See point 13.)

UTC #150 Minutes ( L2/17-016) (See D.11 for decision and action items)