Property and equipment:

9 Months Ended

Sep. 30, 2021

Property and equipment:

Property and equipment:

2.  Property and equipment:

Depreciation and amortization expense related to property and equipment and finance leases was $22.6 million and $21.6 million for the three months ended September 30, 2021 and 2020, respectively, and $66.7 million and $61.0 million for the nine months ended September 30, 2021 and 2020, respectively. The Company capitalized salaries and related benefits of employees working directly on the construction and build-out of its network of $3.1 million and $3.0 million for the three months ended September 30, 2021 and 2020, respectively, and $10.4 million and $8.9 million for the nine months ended September 30, 2021 and 2020, respectively.