June 2017

Investor Presentation

2

Disclaimer

Forward-Looking Statements: This presentation contains forward-looking statements which are made pursuant to

the safe harbor provisions of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the

Securities Exchange Act of 1934, as amended.

The forward-looking statements in this presentation do not constitute guarantees of future performance. Investors are

cautioned that statements in this presentation, which are not strictly historical statements, including, without

limitation, statements by our President and Chief Executive Officer and our Chief Financial Officer, and statements

concerning our expected future performance, plans, objectives and strategies, constitute forward-looking statements.

Such forward-looking statements are subject to a number of risks and uncertainties that could cause actual results to

differ materially from those anticipated by the forward-looking statements, including, without limitation, risks

associated with our ability to develop and market new products and services that meet customer demands and

generate acceptable margins; our reliance on several large customers; our ability to negotiate and enter into

acceptable contract terms with our suppliers; our ability to attract and retain qualified management and other

personnel; competition in the industry in which we do business; failure of the third-party communications networks on

which we depend; legislation or regulatory environments, requirements or changes adversely affecting the

businesses in which we are engaged; our ability to maintain our databases, management systems and other

intellectual property; our ability to maintain adequate liquidity and produce sufficient cash flow to fund our capital

expenditures and debt service; our ability to obtain capital to grow our business; technological developments and

changes in the industry; our ability to complete acquisitions or divestures and to integrate any business or operation

acquired; general economic condition and other risks detailed in our filings with the Securities and Exchange

Commission. We undertake no obligation to update any forward-looking information contained in this presentation.

Additionally, this presentation may contain various non-GAAP financial measures as defined by the SEC’s

Regulation G. More information on the non-GAAP financial measures used in this presentation can be found on the

Investor Relations page of our corporate website at www.gtt.net.

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GTT Overview

Expansive Global

Reach

Comprehensive Cloud

Networking ServicesOutstanding

Client Experience

GTT delivers cloud networking services to multinational clients

Strong Growth Profile

Top five global Tier 1 IP

network; 300+ PoPs worldwidePrivate Networking, Internet,

Optical Transport, Managed

Services, Voice and Video

Differentiated service built on

our core values of simplicity,

speed and agility

LQA Revenue: $729M (47% 5-year CAGR)

LQA Adj. EBITDA: $203M (72% 5-year CAGR)

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Extensive Global Network

1,000+

Points of Presence

(PoPs)Ranked global

Internet backbone(1)

Regional partners for

network extensionsCloud services and

applications available

for seamless access

(1) Source: Dyn Independent Research firm

300+ Top 5

2,000

Client locations100,000+

Sub

59msLowest latency

New York to London

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A Better Way to Reach the CloudConnecting clients to any location in the world and any application in the cloud

Client

Data Center

Security

Services

SIP Trunking

Hosted PBX

Internet Services

EtherCloud®

Wide Area

Networking Services

Tier 1 Global IP

Network

GTT PoP GTT PoP GTT PoP

Client

Branch Office

Secure

Remote Access

Remote Users

Cloud Service Providers

• Leased Ethernet/MPLS/Broadband connections

• Typically purchased back-to-back with customer contracts

• Substantial majority of monthly network spend

• Points of Presence (PoPs) in most major carrier neutral data centers

worldwide

• PoPs are connected via wavelengths; utilize owned routes where available,

lease the rest, typically on 1-yr terms to maintain flexibility and leverage

• Not specific to customer contracts; based on aggregate traffic demand

Core Network Connectivity Last Mile Access

Client

Headquarters

Public

Internet

Private

Connection

Video

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Comprehensive Portfolio of Services

Voice and UC

• SIP Trunking

• Hosted PBX

Managed Services

• Managed Network Services

• Managed Security Services

• Managed Secure Access

• Managed SD-WAN

Video

• Dedicated

• Event Services

Internet

• IP Transit

• Dedicated Internet Access

• Broadband Internet

Private Networking

• Ethernet

• VPLS

• MPLS (IP VPN)

Optical Transport

• Wavelengths

• Low latency

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Diversified Revenue Mix

Customer Type Service Type Geography

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Growth Strategy

Next Financial Objective:

$1 Billion in Revenue, $250 Million in Adjusted EBITDA

• Expand cloud networking services to

multinational clients

• Extend secure network connectivity to

any location in the world and any

application in the cloud

• Deliver outstanding client experience by

living our core values of simplicity,

speed and agility

Execute strategy through organic growth and accretive acquisitions

• ‘Capex Light’ model allows for global

reach and rapid deployment of

bandwidth to meet client needs

• Global scale and top five Tier 1 IP

backbone enable superior services and

value

• Internally developed software platform

(CMD) to handle all aspects of customer

lifecycle and profitability

Drivers Differentiators

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Transformation through Strategic M&AAnnualized Revenue

($ in millions)

Adds enterprise-

grade voice

services

Adds strategic

transatlantic

fiber network

Adds managed

network

servicesCompletes

transformation

to Tier 1 IP

network

Proven Approach

• Strong strategic fit

– Expand services/reach

– Add clients/sales talent

• Rapid integration of

organization, systems and

networks

• Highly accretive based on

multiple of post-synergy

EBITDA

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Financial Highlights($ in Millions)

Note: Financial results are as reported, not including constant currency adjustments and only including acquisitions after their respective close dates

Adjusted EBITDA

Capex Adjusted EBITDA less Capex

Revenue

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As Reported

Pro Forma Financial Highlights($ in Millions)

As Reported Pro Forma

Pro Forma

Note: As reported results include acquisitions only after their respective close dates and do not include constant currency adjustments; pro forma results

include material acquisitions only; pro forma growth rates include constant currency adjustments

Revenue

Adjusted EBITDA

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Liquidity & Leverage

($ in Millions)

(1) Total Debt divided by annualized 1Q17 Adjusted EBITDA; (2) Total Debt less Cash divided by annualized 1Q17 Adjusted EBITDA

• 1Q17 leverage ratios do not include full $30M annualized Hibernia synergy run-rate

• On a pro forma basis including full run-rate synergies, 1Q17 leverage ratios would be

approximately 0.5x lower

• GTT’s long-term target leverage ratio remains 3.0-4.0x

Cash 33.0

Available Revolver 74.3

Total Liquidity 107.3

Term Loan B (L+400bps) 698.3

7.875% Senior Notes 300.0

Capital Leases 0.8

Total Debt 999.1

1Q17 Annualized Adjusted EBITDA 202.9

1Q17 Leverage (1) 4.9x

1Q17 Net Leverage (2) 4.8x

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Investment Highlights

Significant Market

Opportunity

Compelling

Business

Strategy

Experienced

Leadership Team

Proven Track

Record

Superior Financial

Profile

(1) Sources: Cisco Visual Networking Index, 2015-2020, Cisco Global Cloud Index, 2014–2019 White Paper

• IP-based and cloud traffic forecasted to grow rapidly, at 22% and 30% CAGR(1), creating

significant need for bandwidth and networking services

• Increasing complexity of IT and security requirements driving demand for managed services

• Higher propensity to purchase networking services from non-incumbent providers

• Global Tier 1 IP network with top five ranked internet backbone

• Targeting multinational clients underserved by global incumbents

• Trusted by clients to deliver mission-critical services with simplicity, speed and agility

• Significant growth; 47% Revenue CAGR and 72% Adjusted EBITDA CAGR from 2012-2017

• Proven ability to identify, close and integrate accretive acquisitions

• Large, diversified, blue-chip customer base

• Monthly recurring revenue model (90%+ of total revenue) with expanding margins

• Low capital expenditures (6-7% of revenue) delivering strong cash flow

• Strong balance sheet to fund growth

• Deep expertise managing high-growth communications businesses

• Long tenured and experienced board of directors

• Significant management and board ownership

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Non-GAAP Financial InformationGTT GAAP to Non-GAAP Reconciliation

In addition to financial measures prepared in accordance with accounting principles generally accepted in the United States (“GAAP”), from time to time GTT may use or publicly

disclose certain "non-GAAP financial measures" in the course of its financial presentations, earnings releases, earnings conference calls, and otherwise. For these purposes, the

U.S. Securities and Exchange Commission (“SEC”) defines a "non-GAAP financial measure" as a numerical measure of historical or future financial performance, financial

positions, or cash flows that (i) exclude amounts, or is subject to adjustments that effectively exclude amounts, included in the most directly comparable measure calculated and

presented in accordance with GAAP in financial statements, and (ii) include amounts, or is subject to adjustments that effectively include amounts, that are excluded from the most

directly comparable measure so calculated and presented.

Non-GAAP financial measures are provided as additional information to investors to provide an alternative method for assessing GTT’s financial condition and operating results.

GTT believes that these non-GAAP measures, when taken together with its GAAP financial measures, allow the Company and its investors to better evaluate its performance and

profitability. These measures are not in accordance with, or a substitute for, GAAP, and may be different from or inconsistent with non-GAAP financial measures used by other

companies. These measures should be used in addition to and in conjunction with results presented in accordance with GAAP, and should not be relied upon to the exclusion of

GAAP financial measures.

Pursuant to the requirements of Regulation G, whenever GTT refers to a non-GAAP financial measure it will also present the most directly comparable financial measure calculated

and presented in accordance with GAAP, along with a reconciliation of the differences between the non-GAAP financial measure GTT references with such comparable GAAP

financial measure.

Adjusted Earnings before Interest, Taxes, Depreciation and Amortization (“Adjusted EBITDA”)

Adjusted EBITDA is defined by GTT as net income/(loss) before interest and other expense, net, income tax (benefit) expense and depreciation and amortization ("EBITDA")

adjusted to exclude severance, restructuring and other exit costs, acquisition-related transaction and integration costs, losses on extinguishment of debt, share-based

compensation, and from time to time, other non-cash or non-recurring items. Adjusted EBITDA is defined by Hibernia as net income (loss) before interest expense, (benefit from) /

provisions for income taxes and depreciation and amortization adjusted to exclude losses on extinguishment of debt, other costs, net, including foreign currency translation gains

and losses, and from time to time, other non-cash or non-recurring items. The Pro Forma EBITDA and Pro Forma Adjusted EBITDA in this presentation represent GTT’s EBITDA

and Adjusted EBITDA, respectively, after giving effect to the Hibernia’s acquisitions as of the first day of the period presented and adding anticipated estimated cost savings

synergies from the Hibernia acquisition and Adjusted EBITDA from individually immaterial acquisitions after giving effect to such acquisitions as if each had occurred on January 1,

2016. GTT uses Adjusted EBITDA to evaluate operating performance, and this financial measure is among the primary measures we use for planning and forecasting future

periods. GTT further believes that the presentation of Adjusted EBITDA is relevant and useful for investors because it allows investors to view results in a manner similar to the

method used by management and makes it easier to compare GTT’s results with the results of other companies that have different financing and capital structures. However other

companies may define Adjusted EBITDA differently than GTT does, so its Adjusted EBITDA may not be fully comparable with those of other companies. In addition, the Company

has debt covenants that are based on a leverage ratio which utilizes a modified EBITDA calculation, as defined in its credit agreement. The modified EBITDA calculation in GTT’s

credit agreement is similar to its definition of Adjusted EBITDA; however it includes the pro forma Adjusted EBITDA of and expected cost synergies from the companies acquired

by GTT during the applicable reporting period. Finally, Adjusted EBITDA results, along with other quantitative and qualitative information, are utilized by management and GTT’s

compensation committee for purposes of determining bonus payouts to its employees.

Adjusted EBITDA less capital expenditures

Adjusted EBITDA less the cost of purchases of property and equipment during the indicated period , which GTT also refers to as capital expenditures, is a performance measure

that is used to evaluate the appropriate level of capital expenditures needed to support its expected revenue, and to provide a comparable view of GTT’s performance relative to

other telecommunications companies who may utilize different strategies for providing access to fiber-based services and related infrastructure. The Company uses a “capex light”

strategy, which means it purchases fiber-based services and related infrastructure from other providers on an as-needed basis, pursuant to its customers’ requirements. Many

other telecommunications companies spend significant amounts of capital expenditures to construct their own fiber networks and data centers, and attempt to purchase as little as

possible from other providers. As a result of GTT’s strategy, it typically has lower Adjusted EBITDA margins compared to other providers, but also spends much less on capital

expenditures relative to its revenue. GTT believes it is important to take both of these factors into account when evaluating its performance.

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Non-GAAP Financial Information

Pro Forma Financial Information

In addition to financial measures prepared in accordance with GAAP, from time to time we may use or publicly disclose certain "pro forma”

financial measures. We believe certain pro forma financial measures provide a more comparable view of our results relative to prior

periods, particularly given the number of acquisitions we have completed in the past. The following unaudited pro forma financial

information and related notes present the historical financial information of GTT as if the acquisition of Hibernia had occurred on the first

day of the applicable period presented, and do not include any add-backs for expected post-acquisition cost synergies in pre-acquisition

periods. Note: pro forma information is only prepared for material acquisitions.

Constant Currency

We evaluate our results of operations both as reported and on a constant currency basis. The constant currency presentation, which is a

non-GAAP measure, excludes the impact of fluctuations in foreign currency exchange rates. We believe providing constant currency

information provides valuable supplemental information regarding our results of operations, consistent with how we evaluate our

performance. We calculate constant currency results by converting our current period local currency financial results using prior period

exchange rates and comparing these adjusted amounts to our prior period reported results.

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Non-GAAP Reconciliation

($ in Millions)

Adjusted EBITDA 2012 2013 2014 2015 20161Q17

Annualized

Net Income (loss) (1.6)$ (20.8)$ (23.0)$ 19.3$ 5.3$ (52.4)$

Income tax (benefit) expense 0.7 (2.0) 2.1 (34.1) 3.9 (46.0)

Other (income) loss, net 1.1 11.7 8.6 1.2 0.6 0.4

Loss on debt extinguishment - 0.7 3.1 3.4 1.6 22.8

Interest expense, net 4.7 8.4 8.5 13.9 29.4 63.2

Depreciation and amortization 7.3 17.2 24.9 46.7 62.8 121.6

Severance, restructuring and other exit costs 0.7 7.7 9.4 12.7 0.9 42.8

Transaction and integration costs - - - 6.1 4.8 32.4

Non-cash compensation 0.6 1.5 2.4 7.9 15.8 18.1

Adjusted EBITDA 13.5$ 24.3$ 36.1$ 77.0$ 125.0$ 202.9$

Capital expenditures (1.8) (4.1) (5.9) (14.1) (24.2) (33.9)

Adjusted EBITDA less Capex 11.7$ 20.2$ 30.2$ 63.0$ 100.9$ 169.0$

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Non-GAAP Reconciliation (Quarterly)

($ in Millions)

Adjusted EBITDA 1Q16 2Q16 3Q16 4Q16 1Q17

Net Income (loss) 0.9$ 0.1$ 5.1$ (0.9)$ (13.1)$

Income tax (benefit) expense 0.4 0.0 (0.1) 3.6 (11.5)

Other (income) loss, net 0.3 0.2 0.1 0.0 0.1

Loss on debt extinguishment - 1.6 - - 5.7

Interest expense, net 7.4 7.1 7.1 7.8 15.8

Depreciation and amortization 15.6 15.7 14.9 16.6 30.4

Severance, restructuring and other exit costs 1.5 - (0.6) - 10.7

Transaction and integration costs 1.3 1.1 0.8 1.7 8.1

Non-cash compensation 1.6 4.5 4.8 4.9 4.5

Adjusted EBITDA 28.9$ 30.3$ 32.1$ 33.8$ 50.7$

Capital expenditures (7.5) (4.8) (5.5) (6.4) (8.5)

Adjusted EBITDA less Capex 21.3$ 25.5$ 26.6$ 27.4$ 42.3$

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Pro Forma Revenue & EBITDA Summary

($ in Millions)

(1) Represents (i) revenue recognized by acquired companies from GTT prior to their respective close dates, and (ii) adjustments in

deferred revenue from acquired companies

(2) Represents adjustments in deferred revenue from acquired companies

Note: Pro forma adjustments do not include any add-backs for expected cost synergies

1Q16 2Q16 3Q16 4Q16 1Q17

GTT as reported 124.4$ 128.9$ 131.9$ 136.5$ 182.4$

GTT pro forma adjustments - (0.0) (0.0) - -

Hibernia as reported 47.4 45.8 45.5 43.4 -

Hibernia pro forma adjustments (1)(1.5) (1.5) (1.5) (1.5) -

Pro Forma Revenue 170.3$ 173.2$ 175.9$ 178.4$ 182.4$

Pro Forma % Growth - Sequential 4.7% 1.7% 1.5% 1.4% 2.2%

Pro Forma % Growth - Year-over-Year 7.1%

GTT as reported 28.9$ 30.3$ 32.1$ 33.8$ 50.7$

GTT pro forma adjustments - - - - -

Hibernia as reported 17.3 15.8 16.1 16.8 -

Hibernia pro forma adjustments (2)(1.1) (1.1) (1.1) (1.1) -

Pro Forma EBITDA 45.1$ 44.9$ 47.1$ 49.5$ 50.7$

Percentage of Revenue 26% 26% 27% 28% 28%

Pro Forma % Growth - Sequential 14.8% -0.4% 4.8% 5.2% 2.6%

Pro Forma % Growth - Year-over-Year 12.7%