47 CFR § 32.3100 - Accumulated depreciation.
(b) This account shall be credited with depreciation amounts concurrently charged to Account 6561, Depreciation expense - telecommunications plant in service. (Note also Account 3300, Accumulated depreciation - nonoperating.)
(c) At the time of retirement of depreciable operating telecommunications plant, this account shall be charged with the original cost of the property retired plus the cost of removal and credited with the salvage value and any insurance proceeds recovered.
(d) This account shall be credited with amounts charged to Account 1438, Deferred maintenance, retirements, and other deferred charges, as provided in § 32.2000(g)(4) of this subpart. This account shall be credited with amounts charged to Account 6561 with respect to other than relatively minor losses in service values suffered through terminations of service when charges for such terminations are made to recover the losses.