Exhibit 99.1

UNAUDITED PRO FORMA CONDENSED CONSOLIDATED FINANCIAL INFORMATION

On October 23, 2015, Digi International (the Company), completed the sale of its wholly owned subsidiary, Etherios, Inc., to West Monroe Partners, LLC on the terms described in the Company’s Current Report on Form 8-K filed with the SEC on October 26, 2015.

The Company sold Etherios for $9.0 million. This is composed of (1) a payment equal to $4.0 million due at closing less certain transaction costs of approximately $1.1 million withheld for certain employee related liabilities, and (2) additional payments of $3.0 million due on the first anniversary of closing and $2.0 million due on the second anniversary of the closing.

The unaudited pro forma condensed consolidated financial information shown below is based on historical consolidated financial statements of the Company and shows the effect to the disposition of Etherios to be accounted for as a discontinued operation. The accompanying unaudited pro forma condensed consolidated balance sheet as of June 30, 2015 presents the Company’s historical consolidated statement of financial position, giving effect to the disposition as if it had been completed on June 30, 2015. The accompanying unaudited pro forma condensed consolidated statements of operations for the nine months ended June 30, 2015 and for the fiscal years ended September 30, 2014 and 2013 present the Company’s historical consolidated statements of operations, giving effect to the disposition as if it had been completed on October 1, 2012, the beginning of the earliest period presented. The fiscal year ended September 30, 2012 has not been included in the financial information shown below as Etherios was acquired by the Company on October 31, 2012.

The unaudited pro forma condensed consolidated financial statements include factually supportable assumptions and adjustments that are directly related to the disposition. These pro forma adjustments have been made to illustrate the anticipated financial effect of the disposition on the Company. The adjustments are based upon available information and assumptions that the Company believes are reasonable as of the date of this filing. However, actual adjustments may differ materially from the information presented. Assumptions underlying the pro forma adjustments are described in the accompanying notes, which should be read in conjunction with the unaudited pro forma condensed consolidated financial information. The unaudited pro forma condensed consolidated financial statements, including notes thereto, should be read in conjunction with the historical financial statements and notes thereto of the Company included in the Company’s Annual Report on Form 10-K for the year ended September 30, 2014.

DIGI INTERNATIONAL INC.

UNAUDITED PRO FORMA CONDENSED CONSOLIDATED BALANCE SHEET

As of June 30, 2015

(in thousands)	As Reported		Etherios Adjustment (A)			Pro Forma Adjustments			Pro Forma Consolidated
ASSETS
Current assets:
Cash and cash equivalents	$	53,755	$	—		$	2,866	(B)	$	56,621
Marketable securities		37,527								37,527
Accounts receivable, net		24,415		(1,639	)					22,776
Inventories		34,690								34,690
Deferred tax assets		3,072					(105	) (C)		2,967
Other		2,912		(86	)		680	(C)		3,506
Total current assets		156,371		(1,725	)		3,441			158,087
Marketable securities, long-term		9,471								9,471
Property, equipment and improvements, net		14,628		(113	)					14,515
Identifiable intangible assets, net		4,789		(1,652	)					3,137
Goodwill		102,497		(2,153	)					100,344
Deferred tax assets		5,708								5,708
Other		293					4,864	(B)		5,157
Total assets	$	293,757	$	(5,643	)	$	8,305		$	296,419
LIABILITIES AND STOCKHOLDERS’ EQUITY
Current liabilities:
Accounts payable	$	7,048	$	(85	)		—		$	6,963
Accrued compensation		10,464		(1,331	)		—			9,133
Other		3,372		(96	)		1,842	(C)		5,118
Total current liabilities		20,884		(1,512	)		1,842			21,214
Income taxes payable		1,401								1,401
Deferred tax liabilities		151		(645	)					(494	)
Other noncurrent liabilities		678		(96	)					582
Total liabilities		23,114		(2,253	)		1,842			22,703
Stockholders’ equity		270,643		(3,390	)		2,271	(B)		273,716
							575	(C)
							3,617	(D)
Total liabilities and stockholders’ equity	$	293,757	$	(5,643	)	$	8,305		$	296,419

See Notes to Unaudited Condensed Consolidated Pro Forma Financial Statements

DIGI INTERNATIONAL INC.

UNAUDITED PRO FORMA CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS

For the Nine Months Ended June 30, 2015

(in thousands, except per share data)	As Reported			Etherios Adjustment (A)			Pro Forma Adjustments		Pro Forma Consolidated
Revenue:
Hardware product	$	143,042		$	—		$	—	$	143,042
Service revenue		13,370			(6,738	)		—		6,632
Total revenue		156,412			(6,738	)		—		149,674
Cost of sales:
Cost of product		74,339			—			—		74,339
Cost of service		10,724			(6,205	)		—		4,519
Total cost of sales		85,063			(6,205	)		—		78,858
Gross profit		71,349			(533	)		—		70,816
Operating expenses:
Sales and marketing		30,525			(1,433	)		—		29,092
Research and development		23,715			(1,567	)		—		22,148
General and administrative		14,448			(850	)		—		13,598
Restructuring charges, net		509			(106	)		—		403
Total operating expenses		69,197			(3,956	)		—		65,241
Operating income		2,152			3,423			—		5,575
Other income, net:
Interest income		137			—			—		137
Interest expense		(3	)		—			—		(3	)
Other income, net		2,131			—			—		2,131
Total other income, net		2,265			—			—		2,265
Income before income taxes		4,417			3,423			—		7,840
Income tax provision		814			1,261			—		2,075
Net income from continuing operations	$	3,603		$	2,162		$	—	$	5,765
Earnings per share from continuing operations:
Basic	$	0.15							$	0.24
Diluted	$	0.14							$	0.23
Weighted average common shares:
Basic		24,525								24,525
Diluted		25,085								25,085

See Notes to Unaudited Condensed Consolidated Pro Forma Financial Statements

DIGI INTERNATIONAL INC.

UNAUDITED PRO FORMA CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS

Fiscal Year Ended September 30, 2014

(in thousands, except per share data)	As Reported			Etherios Adjustment (A)			Pro Forma Adjustments		Pro Forma Consolidated
Revenue:
Hardware product	$	172,846		$	—		$	—	$	172,846
Service revenue		19,855			(9,528	)		—		10,327
Total revenue		192,701			(9,528	)		—		183,173
Cost of sales:
Cost of product		85,737			—			—		85,737
Cost of service		16,480			(9,421	)		—		7,059
Total cost of sales		102,217			(9,421	)		—		92,796
Gross profit		90,484			(107	)		—		90,377
Operating expenses:
Sales and marketing		40,576			(1,825	)		—		38,751
Research and development		29,789			(877	)		—		28,912
General and administrative		19,913			(1,669	)		—		18,244
Restructuring charges, net		81			—			—		81
Total operating expenses		90,359			(4,371	)		—		85,988
Operating income		125			4,264			—		4,389
Other income, net:
Interest income		176			—			—		176
Interest expense		(5	)		—			—		(5	)
Other income, net		501			—			—		501
Total other income, net		672			—			—		672
Income before income taxes		797			4,264			—		5,061
Income tax provision		(954	)		1,522			—		568
Net income from continuing operations	$	1,751		$	2,742		$	—	$	4,493
Earnings per share from continuing operations:
Basic	$	0.07							$	0.18
Diluted	$	0.07							$	0.17
Weighted average common shares:
Basic		25,345								25,345
Diluted		25,730								25,730

See Notes to Unaudited Condensed Consolidated Pro Forma Financial Statements

DIGI INTERNATIONAL INC.

UNAUDITED PRO FORMA CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS

Fiscal Year Ended September 30, 2013

(in thousands, except per share data)	As Reported			Etherios Adjustment (A)			Pro Forma Adjustments		Pro Forma Consolidated
Revenue:
Hardware product	$	173,078		$	—		$	—	$	173,078
Service revenue		22,303			(10,961	)		—		11,342
Total revenue		195,381			(10,961	)		—		184,420
Cost of sales:
Cost of product		82,276			—			—		82,276
Cost of service		12,982			(6,163	)		—		6,819
Total cost of sales		95,258			(6,163	)		—		89,095
Gross profit		100,123			(4,798	)		—		95,325
Operating expenses:
Sales and marketing		40,513			(1,284	)		—		39,229
Research and development		30,327			(1,245	)		—		29,082
General and administrative		21,423			(2,006	)		—		19,417
Restructuring charges, net		313			—			—		313
Total operating expenses		92,576			(4,535	)		—		88,041
Operating income		7,547			(263	)		—		7,284
Other income, net:
Interest income		210			—			—		210
Interest expense		(42	)		4			—		(38	)
Other income, net		523			—			—		523
Total other income, net		691			4			—		695
Income before income taxes		8,238			(259	)		—		7,979
Income tax provision		2,433			(103	)		—		2,330
Net income from continuing operations	$	5,805		$	(156	)	$	—	$	5,649
Earnings per share from continuing operations:
Basic	$	0.22							$	0.22
Diluted	$	0.22							$	0.22
Weighted average common shares:
Basic		25,956								25,956
Diluted		26,237								26,237

See Notes to Unaudited Condensed Consolidated Pro Forma Financial Statements

DIGI INTERNATIONAL INC.

NOTES TO UNAUDITED PRO FORMA CONDENSED CONSOLIDATED FINANCIAL INFORMATION

As of June 30, 2015 and for the Nine Months Ended June 30, 2015

and the Fiscal Years Ended September 30, 2014 and 2013

Pro Forma Adjustments to the Unaudited Pro Forma Condensed Consolidated Balance Sheet as of June 30, 2015

(A) To eliminate the assets and liabilities sold in the disposition of the Etherios business.

(B) To record the estimated fair value of the consideration received of $7.8 million. The $7.8 million is comprised of cash proceeds of $2.9 million ($4.0 million of initial selling price less $1.1 million withheld for certain employee related liabilities) and $4.9 million of payments due to the Company during the next two years. The remaining $4.9 million is the discounted value of the $3.0 million due on the first anniversary of closing and the additional $2.0 million due on the second anniversary of closing.

(C) To record additional expenses of $1.8 million related to facility costs, professional service fees, severance and other employee costs that are directly attributed to the disposition of Etherios and related income tax benefit.

(D) To record the estimated gain of $5.4 million on disposition, less additional expenses of $1.8 million incurred as described in Note C above. The estimated gain and the additional expenses have not been reflected in the unaudited pro forma condensed consolidated statement of operations as they are considered to be nonrecurring in nature.

Pro Forma Adjustments to the Unaudited Pro Forma Condensed Consolidated Statements of Operations for the Nine Months Ended June 30, 2015 and the Fiscal Years ended September 30, 2014 and 2013

(A) To eliminate the revenues and direct expenses of Etherios, including the estimated income tax effect of the pro forma adjustments.