Our revenue from our net-centric customers increased primarily due to an increase in our number of net-centric customers and growth in network traffic from these customers and from net-centric customer connections acquired with the Sprint Business. Our net-centric customers purchase our services on a price per megabit basis. The net-centric market exhibits significant pricing pressure due to the continued introduction of new technology, which lowers the marginal cost of transmission and routing, and the commodity nature of the service where price is typically the only differentiating factor for these customers. Our average price per megabit of our installed base of customers decreased by 5.8% from the nine months ended September 30, 2022 to the nine months ended September 30, 2023. The impact of foreign exchange rates has a more significant impact on our net-centric revenues.
Revenue and customer connections by network connection type
Our on-net revenues increased by 10.7% from the nine months ended September 30, 2022 to the nine months ended September 30, 2023. Our on-net revenues increased as we increased the number of our on-net customer connections by 8.5% at September 30, 2023 from September 30, 2022. On-net customer revenues increased at a greater rate than on-net customer connections primarily due to an increase in our on-net ARPU from the nine months ended September 30, 2022 to the nine months ended September 30, 2023. ARPU is determined by dividing revenue for the period by the average customer connections for that period. On-net revenues from customers acquired in the Sprint Business was $10.4 million from May 1, 2023 (the closing date) to September 30, 2023.
Our off-net revenues increased by 147.3% from the nine months ended September 30, 2022 to the nine months ended September 30, 2023. Our off-net revenues increased primarily from the increase in the number of our off-net customer connections from September 30, 2022 to September 30, 2023. Off-net revenues from customers acquired in the Sprint Business were $156.4 million from May 1, 2023 (the closing date) to September 30, 2023.
In connection with our acquisition of the Sprint Business, we expanded our offering of optical wavelength and optical transport services over our fiber network. Wavelength revenues from customers acquired in the Sprint Business were $4.6 million from May 1, 2023 (the closing date) to September 30, 2023.
Our non-core revenues increased from the nine months ended September 30, 2022 to the nine months ended September 30, 2023 primarily from the acquisition of non-core revenues from customers acquired in the Sprint Business. Non-core revenues from customers acquired in the Sprint Business were $19.7 million from May 1, 2023 (the closing date) to September 30, 2023.
Network Operations Expenses. Network operations expenses include the costs of personnel associated with service delivery, network management and customer support, network facilities costs, fiber and equipment maintenance fees, leased circuit costs, access and facilities fees paid to building owners and excise taxes billed to our customers and recorded on a gross basis. Our network operations expenses, including non-cash equity-based compensation expense, increased by 116.0% from the nine months ended September 30, 2022 to the nine months ended September 30, 2023. Non-cash equity-based compensation expense is included in network operations expenses consistent with the classification of the employee’s salary and other compensation. The increase in network operations expense is primarily attributable to an increase in costs related to our network and facilities expansion activities, an increase in power costs and $174.0 million of network operations expense from our acquisition of the Sprint Business from May 1, 2023 (the closing date) to September 30, 2023.
Selling, General, and Administrative (“SG&A”) Expenses. Our SG&A expenses, including non-cash equity-based compensation expense, increased by 62.9% from the nine months ended September 30, 2022 to the nine months ended September 30, 2023. Non-cash equity-based compensation expense is included in SG&A expenses consistent with the classification of the employee’s salary and other compensation. SG&A expenses increased primarily from an increase in salaries and benefits from an 91.2% increase in our total headcount, including 942 employees added to our headcount from our acquisition of the Sprint Business. Our sales force headcount, inclusive of sales management, was 833 at September 30, 2023 and 669 at September 30, 2022, and our total headcount was 1,990 at September 30, 2023 and 1,041 at September 30, 2022. The Sprint Business added 114 employees to our sales force headcount. SG&A expense from our acquisition of the Sprint Business was $73.1 million from May 1, 2023 (the Closing date) to September 30, 2023.
Depreciation and Amortization Expenses. Our depreciation and amortization expense increased by 139.4% from the nine months ended September 30, 2022 to the nine months ended September 30, 2023. The increase is primarily due to the depreciation expense associated with the increase in deployed fixed assets and $86.1 of depreciation and amortization expense from assets, including a finance lease totaling $160.9 million being amortized over forty-four months, acquired with the Sprint Business.