Wholesale SIP Trunking for Resellers and MSPs: How It Works and What to Ask

Quick answer: what is wholesale SIP trunking?

Wholesale SIP trunking is voice termination and origination sold in bulk to companies that resell it, rather than to the business making the calls. Buyers are MSPs, VoIP resellers, UCaaS and CCaaS platforms, PBX installers and call-center software vendors who bundle the minutes into their own product. Wholesale rates are lower than retail (often 30 to 50 percent below published pay-as-you-go prices) in exchange for volume commitments, and the reseller owns the customer relationship, billing and first-line support. Signalmash offers wholesale SIP with direct Tier-1 routes, white-label number management and a partner program for resellers.

This article is part of the Signalmash SIP trunking resource series: what SIP trunking is, the best providers in 2026, what it costs, wholesale SIP for resellers and Twilio Elastic SIP alternatives.

If you install PBXs, run a managed service practice or build a software product that makes phone calls, you eventually face the same decision: keep sending your customers to a retail carrier, or buy voice at wholesale and make it part of what you sell. This guide covers how wholesale SIP works, what a reseller needs from a carrier, how the margins look, and the questions to ask before you sign.

Retail vs wholesale SIP trunking

	Retail	Wholesale
Buyer	The business making calls	A reseller, MSP or platform
Pricing	Published per-minute or per-channel	Negotiated rate deck, volume tiers
Commitment	None or small	Monthly minimum or prepaid balance
Numbers	Provider portal, per number	Bulk ordering and porting via API, white-label
Support	Provider supports the end user	Carrier supports the reseller; reseller supports the customer
Billing	Provider bills the customer	Reseller bills; carrier provides CDRs

Who buys wholesale SIP

• Managed service providers and PBX installers who want recurring voice revenue alongside hardware and support contracts.
• UCaaS and CCaaS platforms that need carrier services under their own brand, or that let customers bring their own carrier.
• SaaS products with voice features: CRMs, dialers, appointment tools, telehealth platforms.
• Regional VoIP providers that want direct routes into AT&T, Verizon and T-Mobile without building interconnects themselves.
• Call center operators running multiple client campaigns who buy at wholesale and allocate cost per client.

What a reseller needs from a wholesale carrier

Direct routes and route quality

Ask who the carrier interconnects with. A wholesale provider that resells another aggregator adds a hop, a margin and a support layer between you and the problem. Signalmash connects directly to AT&T, Verizon, T-Mobile and Bandwidth, so your customers' calls take one hop to the terminating carrier.

Numbers at scale

Bulk ordering, bulk porting with LOA management, CNAM, E911 provisioning with dispatchable location, and toll-free RespOrg services, all available through an API so they can be built into your own portal.

STIR/SHAKEN and reputation

Since 2021 every US voice provider must sign calls. A wholesale carrier should give your traffic full (A-level) attestation where you control the numbers, support branded caller ID, and help you keep numbers off Scam Likely lists. See why business calls get marked Scam Likely.

Multi-tenant management

Sub-accounts per customer, per-account trunks and credentials, per-account spend limits, and CDRs you can pull per sub-account for billing.

Fraud controls

Per-trunk spend caps, geographic restrictions, concurrent-call limits and real-time alerts. On wholesale volumes a compromised customer PBX can run up thousands of dollars in an hour.

Support that matches your SLA

If you promise customers a four-hour response, your carrier needs to answer you faster than that. Signalmash puts partners in a shared Slack channel with network engineers rather than a ticket queue.

Messaging on the same numbers

Customers increasingly expect SMS from their business numbers. A carrier that offers SMS, MMS and RCS on the same DIDs, with 10DLC and toll-free verification handled, lets you sell one bundle instead of two vendors.

Margins: how the numbers work

Retail per-minute prices in the US sit around $0.007 to $0.014 per minute outbound. Wholesale decks from carriers with their own routes run from roughly $0.003 to $0.006 depending on volume and destination mix. A reseller that buys at $0.0045 and sells at $0.009 keeps 50 percent gross margin on minutes, plus margin on numbers ($0.50 wholesale, $1.50 to $3 retail is common) and on services (porting, E911, recording, support). A 50-customer MSP practice with 1.5 million minutes a month at those numbers clears roughly $6,000 a month on voice before support costs.

Wholesale vs the Signalmash partner program

Signalmash works with resellers two ways. Wholesale: you hold the carrier relationship, buy at a volume rate deck, manage sub-accounts through the portal or API and bill your customers. Referral and affiliate partnership: you introduce customers who contract directly with Signalmash and you earn a recurring share, with no billing or support burden. Many PBX installers start with referrals and move to wholesale once their voice base is large enough to justify running billing.

Questions to ask before signing a wholesale agreement

1. Which carriers do you interconnect with directly, and can I see a route quality report?
2. What are the volume tiers, minimums and billing increments (1 second, 6 seconds, 60 seconds)?
3. How are high-cost zones and toll-free inbound priced?
4. Do I get an API for numbers, porting, E911, CNAM and CDRs?
5. What attestation level will my traffic receive under STIR/SHAKEN?
6. What fraud controls exist per sub-account, and who eats the loss if they fail?
7. What is the escalation path and response time for a route outage?
8. Can my customers get SMS, MMS and RCS on the same numbers?

Getting started with Signalmash wholesale SIP

Bring an estimate of monthly minutes, number counts and your customer profile (office PBX, contact center, software platform) and Signalmash will quote a rate deck and tier. Details of the retail product are on the SIP trunking page; wholesale and partner terms are quoted directly.

Talk to a Signalmash voice engineer about your call volumes, PBX and number inventory, and we will quote a SIP trunk with the exact per-minute rates you will pay.

People also ask

What is the difference between wholesale and retail SIP trunking?

Retail SIP trunking is sold to the business that makes the calls at published rates with little or no commitment. Wholesale SIP trunking is sold in volume to resellers, MSPs and platforms at a negotiated rate deck; the reseller owns billing, first-line support and the customer relationship and keeps the margin between wholesale and retail prices.

How do I become a SIP trunking reseller?

Choose a wholesale carrier with direct routes and an API, sign a volume agreement, set up sub-accounts and trunks for each customer, build or buy a billing system that rates the carrier's CDRs, and provide first-line support. Many resellers start with a referral or affiliate partnership, such as the Signalmash partner program, before taking on wholesale billing.

What margin can a SIP trunk reseller make?

Typically 40 to 60 percent gross margin on minutes when buying at $0.003 to $0.006 per minute and selling at $0.008 to $0.014, plus margin on number rental, E911, recording and support. Margin is highest for resellers who bundle voice with PBX management or software rather than competing on minutes alone.

Can a wholesale SIP provider offer white-label service?

Yes. Good wholesale carriers provide unbranded number management, porting, E911 and CDR access through an API so resellers can present everything under their own brand and portal. Signalmash supports white-label number management and sub-accounts for partners.