Wholesale SIP Trunking for Carriers and Providers
Horizon Communications Group is a wholesale SIP trunking provider for carriers, CLECs, CPaaS and UCaaS platforms, and resellers. Founder-led since 1998, we provision concurrent-call capacity over direct tier-1 interconnects, with redundant routing and traffic security on every trunk.
What is wholesale SIP trunking?
A SIP trunk is a virtual connection that carries voice calls over IP between your softswitch, PBX, or platform and a carrier network, replacing physical TDM lines such as PRIs. Capacity is measured in concurrent calls rather than fixed circuits.
Wholesale SIP trunking delivers that connectivity in bulk. As a wholesale sip trunk provider, Horizon sizes trunks to your busy-hour volume and lands them on direct interconnects, so your sip trunking services run over a short, well-peered path.
Why providers route SIP trunking through Horizon
Founder-led since 1998
You reach a desk that has provisioned and interconnected SIP trunks for 28 years, not a ticket queue.
Direct tier-1 interconnects
Trunks land on direct interconnects with major networks, so signaling and media take a short, well-peered path.
Redundant routing
Capacity is provisioned with failover paths, so a single route degrading does not take your concurrent calls down.
Security on the path
Fraud management and traffic monitoring watch the trunk for anomalies, not after a bill arrives.
How wholesale SIP trunking works
- 01
Consult
We size the trunk to your busy-hour concurrent calls and confirm codecs, signaling, and the networks you need to reach.
- 02
Provision and interconnect
We provision channels, set up SIP authentication or IP allow-listing, and bring the trunk up against direct interconnects.
- 03
Monitor and optimize
We watch quality and capacity, adjust routing, and add channels or redundancy as your concurrent-call volume grows.
Who SIP trunking is for
- Carriers
- Add or supplement termination and origination capacity without building every interconnect.
- CLECs
- Carry subscriber voice over IP trunks with the numbering and routing handled together.
- CPaaS and UCaaS providers
- Back your platform with wholesale concurrent-call capacity that scales with usage.
- Enterprises
- Replace legacy PRIs with SIP capacity sized to real busy-hour demand.
- Resellers
- Resell trunking under your own brand with a wholesale desk behind it.
SIP trunking FAQ
What is SIP trunking?
A SIP trunk is a virtual connection that carries voice calls over IP between your softswitch, PBX, or platform and a carrier network, replacing physical TDM lines such as PRIs. Wholesale SIP trunking delivers that connectivity in bulk to carriers and providers, with capacity measured in concurrent calls rather than fixed copper circuits.
How does SIP trunking work?
Your platform establishes a SIP session with the carrier using SIP signaling for call setup and RTP for the media. Calls then route over the trunk to the PSTN through the carrier interconnects. Authentication is handled by SIP credentials or IP allow-listing, and the number of simultaneous calls the trunk can carry is set by the channels provisioned.
How many concurrent calls can a SIP trunk handle?
A SIP trunk supports as many simultaneous calls as the channels provisioned on it. Wholesale trunks are provisioned to your needs and scale well beyond what a single PRI allowed, so the practical limit is the capacity you order and the bandwidth available, not a fixed circuit count.
How many SIP trunks do I need?
Size to your busy-hour concurrent calls: the most simultaneous calls you expect at peak, plus headroom for growth and redundancy. Many providers run one logical trunk with enough channels for peak load, split across redundant paths. We size it with you during the consult so you are not guessing.
Ready to size a wholesale SIP trunk?
Tell the desk your busy-hour concurrent calls and the networks you need to reach. We will provision capacity and interconnects to match.