Integrating diverse communication capabilities onto a single global platform is key for the modern Enterprise.  Our Voice service supports PSTN calling, global termination, and emergency services, all delivered via pre-established secure connections to major cloud phone providers.

Pre-established Secure Connections to Key Cloud Phone Providers

Cloud phone systems are rapidly growing in the enterprise market and have changed the way we work and communicate. Cloud Phone Direct is our SIP Trunking offering that supports direct routing to Microsoft Teams, Cisco Webex Calling and Zoom Phone for your voice needs.

GTT Cloud Phone Direct

2. CISCO Webex Calling

CISCO Webex Calling


Our SIP Trunking service can provide Cloud Connected PSTN (CCP) capabilities for Cisco Webex Calling clients. You can make inbound and outbound telephone calls using telephone numbers assigned by or ported to GTT.


3. Microsoft Teams

Microsoft Teams


We can deliver dedicated SIP trunks to Microsoft Teams services residing in Office 365. As a Tier 1 ISP, GTT peers directly with Microsoft, ensuring the lowest latency connectivity between our voice network and Microsoft Office 365.

4. Zoom Phone

Zoom Phone


With Zoom’s BYOC feature, you can use GTT SIP Trunking together with the Zoom Phone cloud. You can enjoy all of the benefits and features of Zoom Phone while benefiting from our global voice solution for outbound calling, as well as new and ported DIDs.

Related Services

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Contact Us
Contact Us
Sales Inquiries:
+1 512 592 4858
General Inquiries:
+1 703 442 5500
Toll Free: +1 855 829 9900 Non Toll Free: +1 512 592 4803
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