The following sections and tables provide details of selected balance sheet items (in thousands):

	As of
	July 31, 2020		January 31, 2020
Finished goods	$	7,098	$	6,988
Raw materials		2,151		1,381
Total inventory	$	9,249	$	8,369

	As of
	July 31, 2020		January 31, 2020
Customer relationships	$	5,334	$	5,841
Developed technology		521		622
Trade names		310		355
Total intangible assets	$	6,165	$	6,818

Amortization expense for acquired intangible assets was $0.3 million for each of the three months ended July 31, 2020 and 2019 and $0.7 million and $0.5 million for the six months ended July 31, 2020 and 2019, respectively.

	As of
	July 31, 2020		January 31, 2020
Deferred sales commissions, current	$	3,573	$	2,525
Prepaid expenses		2,813		2,739
Convertible note receivable, including accrued interest		1,527		1,453
Deferred inventory costs		511		867
Other current assets		1,472		1,408
Total other current assets	$	9,896	$	8,992

Deferred sales commissions, non-current	$	9,154	$	7,412
Other non-current assets		664		774
Total other non-current assets	$	9,818	$	8,186

Deferred Sales Commissions. Amortization expense for deferred sales commissions was $0.9 million and $0.4 million for the three months ended July 31, 2020 and 2019, respectively, and $1.7 million and $0.8 million for the six months ended July 31, 2020 and 2019, respectively. To date, there have been no material impairment losses related to the costs capitalized.

Global Telecomm Corporation. In December 2018, the Company invested $1.3 million in cash to Global Telecomm Corporation, a small privately-held technology company, in exchange for an 18-month convertible promissory note, bearing interest at 10% annually, that will convert to shares of GTC common or preferred stock upon the occurrence of certain future events. During the second quarter of fiscal 2021, the Company executed an amended agreement with GTC that extended the maturity date of the convertible promissory note by nine months from June 30, 2020 to March 31, 2021.

The Company has partnered with GTC on certain research and development and inventory procurement activities. GTC is considered a variable interest entity (“VIE”) for accounting purposes. However, the Company is not required to consolidate GTC into its financial statements because the Company is not the primary beneficiary. As of July 31, 2020 and January 31, 2020, the Company’s maximum exposure to loss was equal to the carrying value of its convertible note receivable and associated interest receivable. For all periods presented, the Company had no other variable interests in VIEs.

GTC is a related party of Ooma as a result of the convertible note. As of July 31, 2020 and January 31, 2020, the Company recorded inventory prepayments to GTC of $0.3 million and $0.5 million, respectively, included in other current assets on the consolidated balance sheet. As of July 31, 2020 and January 31, 2020, the Company’s non-cancelable purchase commitments with GTC were $0.4 million and $2.2 million, respectively.

	As of
	July 31, 2020		January 31, 2020
Payroll and related expenses	$	7,348	$	8,942
Regulatory fees and taxes		5,156		4,777
Short-term operating lease liabilities		3,835		3,263
Customer sales incentives		1,090		1,293
Other		4,085		4,301
Total accrued expenses	$	21,514	$	22,576