If you are buying SIP capacity in volume to supply your own customers, the offer in front of you describes a route: destinations, rates, a technical spec. Your customers will not experience a route. They will experience calls that connect or do not, caller IDs that get labelled or do not, and numbers that work on Monday and are dead on Thursday. This article is about the gap between those two descriptions, and about who answers for which part of it.
A company that resells SIP trunking is not reselling a route — it is taking on an operating responsibility for its customers' calls, and the contract with the upstream provider decides which failures (blocked caller IDs, dead numbers, end-client compliance) land on the reseller and which the upstream absorbs. Read that as a reason to open the agreement before the rate sheet.
Where the first hit lands
You resell under your own contract with your clients; every end client passes KYC. Your end client has no contract with your upstream, so the only party they can hold to account is you. That one fact decides where an incident arrives first, whatever caused it.
A blocked or labelled caller ID. Your end client sees answer rates fall and calls you. Whether the cause is their own calling pattern or the reputation of the number, you are the one who has to explain it and the one who has to produce a fix. What you can fix depends on what your upstream will do about a number: replace it, how fast, and whether your customer has to prove anything again to get a new one.
A dead number. An inbound line that stops delivering is your customer's missing sales call or support queue. The questions for the agreement are who notices first, who tells whom, and who holds the stock to put a working number in its place.
An end-client complaint. If your end client has a complaint about a call, you are the party they can reach.
The end client's compliance file. If a number cannot be issued until a document set is reviewed, someone has to collect that set from your end client. Ask whether your own registration can stand in for theirs, since the next section stays on that question.
The end client's documents are the plot, not a footnote
On VoipTower's outbound pools, the documents required are the end-client KYC set shown for the direction. For a customer who supplies traffic as a transit or reseller account, those are the documents of their end client. The transit company's own papers do not substitute.
The consequence follows directly from that rule. If you resell, collecting and keeping a document set per end client becomes part of your job, because your own registration cannot stand in for theirs. Build that step into the way you take on customers before you commit to volume, not after the first order stalls on a missing file.
On the VoipTower side, the mechanics around those documents work like this. Standard company KYC — company registration, director ID and use case — is done once for a company, which receives a KYC token that is reused on later orders, so a re-order does not restart verification. Directions with a Local document scope also need proof of a local address. The document list for each direction is on the pricing page. Compliance review happens before provisioning, not after a problem shows up. A caller ID is allowed only on a number bought through VoipTower or verified as ported in. None of this removes the need for your end client's documents — for each end client, on its first order in a direction.
The responsibility map
The table below is the working tool of this article. Each row is a responsibility in a reseller chain. The columns do not assert how any given agreement reads. They give you a way to mark up your own contract: for each row, find the clause that moves it, or find that no clause does.
| Responsibility | Yours unless the agreement says otherwise | The upstream's where the agreement says so |
|---|---|---|
| Relationship with the end client | Support, invoicing, expectations | Not applicable: the upstream has no contract with them |
| The end client's documents | Collecting, holding and refreshing them | Reviewing them before numbers are issued |
| Capacity planning | Forecasting your customers' call volume | Capacity limits, and what happens above them |
| Route quality | Reporting symptoms with evidence | Selecting and watching the route |
| Replacing a degraded number | Requesting it, informing your customer | Providing the replacement and the stock behind it |
| Isolation between customers | Your own separation of your customers' traffic | Keeping one customer's numbers apart from another's |
| Compliance before provisioning | Passing the right documents to the right party | Running the review before anything is issued |
Two shapes of upstream offer
Compare two shapes. In the first, the upstream gives you routes and rates, and the agreement describes the connection. In the second, a managed layer sits on top of the routes: someone selects them for your customer, watches them, and replaces what degrades. Neither shape needs a verdict from this article. The useful question is which work lands on your side of the contract in each.
Here is how VoipTower's managed layer is scoped, so you can set it beside whatever else you are reading. On the directions listed for outbound pools on the pricing page, number pools are built individually for each customer instead of being pulled from a shared bulk list; on the other served directions, outbound goes over DID numbers on the customer's account on that direction. Answer rate, call setup time and spam labels on pool numbers are monitored, and a number that degrades is replaced from the stock held for your end client; if you want to be told about each replacement, we do that. The customer can also ask for a replacement. A replacement does not need new documents, because of the KYC token. A pool is built for one customer only, so another customer's traffic cannot affect the reputation of its numbers.
Read this as a mechanism, not a promise of outcomes. The quality described is consistent quality for a customer whose traffic is clean, held on the pool directions listed on the pricing page. There is no answer-rate figure behind it, and a number can still receive a spam label. What the pool offers is detection, replacement and isolation, which are three rows of your map that otherwise fall to you.
Destinations outside the served directions are a different case. Any other country is available only as a managed route on request, after the destination has been vetted, and nothing is promised for a direction until that vetting is done. If an offer you are reading presents every country as an open self-serve list, ask what its quality commitment says about the long tail, and under what conditions the commitment applies.
Capacity, fair use and what a bill can contain
If your customers do not forecast their own volume, you will be the one forecasting it, so how an upstream treats volume matters to you.
On VoipTower outbound pools, a cap on call attempts per number per day is part of the offer, and sustained volume above the cap is not a violation. It is the signal to add numbers to the pool, so the cap works as capacity planning and not as a penalty. Separately, calls above the configured capacity are rejected, not charged at a premium, and billing of a call starts at answer, so post-dial delay is not billed.
Put the same questions to any other agreement: what happens to calls above the limit, and is a per-number cap a penalty trigger or a planning signal? For VoipTower outbound pools there is no per-seat and no per-channel fee: a pool per direction, extra numbers added per month, traffic billed per minute at the pool rate.
Questions to take to the upstream, drawn from the map
You do not need a checklist from outside. The map already generates your questions, one for each row where you found no clause.
Who replaces a blocked number, how quickly, and from what?
If the answer is "we will look into it", you have found a row that stays with you. If the answer names a stock held for your customer and says whether new documents are needed, you can price that row into your own offer.
Is any quality commitment conditional?
Ask whether the commitment depends on the kind of traffic your customers send, and how the upstream decides that traffic is not clean. VoipTower states its condition openly: quality is held for clean traffic, and results for traffic that is not clean are not promised. Whatever you are offered, ask for the condition in writing, since you will be the one explaining it to your customer.
Which timeline is being quoted?
Review of an account request, the first number in a new country, and a re-order for a customer with a token and a previous order in that country are three different timelines. At VoipTower the first is a review of the request, the second is bound by the country's regulator and carrier, and the third is delivered from the customer's stock. The current first-number ETA for a country is on the pricing page. Do not accept one figure that blends the three.
Is there a minimum term, and on which direction?
At VoipTower the minimum term of a DID number depends on the direction; it is shown on the pricing page and in the order form, and confirmed before payment. Outbound pools are billed monthly. Ask for the equivalent in writing from any other upstream.
Where this leaves you
If you are an integrator, a BPO or a small operator supplying voice to customers of your own, the map above is a way to read an agreement as a division of failures instead of a division of routes. VoipTower is one answer to the question of who owns what: a managed layer on the pool directions listed on our pricing page, scoped as described above. The product is described on the wholesale SIP page and the connection side on the SIP trunking page; rates are on the pricing page.
Whichever upstream you pick, mark the map before you sign. For every row, ask which clause moves it, and ask what you will do about each row where the answer is none.
For other partner arrangements, see our partner terms.