Choose source-IP authorization or SIP registration
DIDforSale documents a portal-approved source IP or FQDN path and a separate SIP-account path with a username, password and domain. The IP record must have termination enabled before it can originate calls; the credential path is positioned for systems behind a firewall or devices that require registration. Record the selected model, signaling target, address or credential owner and international-calling policy before configuring the PBX.
Do not leave both paths partially active or use a successful REGISTER as proof that source-IP authorization is correct. The portal account, activated SIP account, allowed address, registration and completed outbound call are different states. Protect credentials and retain one bounded, redacted exchange for the path in use.
Documented service facts
Reviewed 2026-09-28. Compare SIP trunk services →
Authentication
DocumentedDIDforSale documents two interconnection paths: portal-approved source IP or FQDN, and a separately created SIP username, password and domain. The IP record must have termination enabled before it can originate calls. Record one intended model, credential or address owner and international-calling policy; do not leave both paths active by assumption.
SIP registration
DocumentedThe credential path is documented for PBXs behind a firewall or devices that require SIP registration; the source-IP path instead authorizes traffic from a portal record. An activated SIP account, an allowed address, a successful REGISTER and a completed call remain separate evidence states.
Inbound delivery
DocumentedA portal-approved IP or FQDN can be used to configure local and toll-free numbers for delivery, and DIDforSale publishes multiple inbound gateway addresses that customer firewalls must accept. Preserve the exact number route, destination address, provider sources, called-party format and PBX context rather than treating outbound authorization as inbound proof.
Inbound failover
Not verifiedDIDforSale says calls can arrive from several gateway IPs for load balance and uptime, but the reviewed public pages do not define customer destination priority, health checks, timeout, retry order or established-call survival. Accepting every published provider source is an ingress requirement, not proof of customer-side failover.
Number and regional availability
Not verifiedThe current service and pricing pages advertise local and toll-free numbers across more than 13,000 US and Canadian rate centers plus porting. Exact inventory, portability, activation, identity requirements, caller-ID rights and number features remain specific to number, account and date and must be confirmed in the ordering workflow.
Audio codecs
DocumentedDIDforSale lists G.711, G.729, u-law and A-law for its SIP trunks. That list does not prove availability on every destination, license entitlement, DTMF behavior or the payload selected by a call. Capture the offer, answer, RTP payloads and any transcoding for each required route.
T.38 fax
Not verifiedThe reviewed trunk pages do not establish T.38 support, fallback rules or route-specific fax behavior. Separate fax-by-email references and PBX interoperability listings are not proof that a customer trunk negotiates T.38 or carries in-band fax reliably. Qualify the exact number, direction, gateway and approved document set.
Signaling and media encryption
Not verifiedSource-IP authorization and DIDforSale's security marketing do not establish TLS signaling, certificate validation, SRTP media or a downgrade policy for this trunk. The reviewed public setup pages do not publish a trunk-specific TLS/SRTP procedure. Obtain supported transports and profiles in writing and verify the negotiated customer-facing leg.
Concurrent calls and call starts
Not verifiedDIDforSale prices some inbound plans by simultaneous-call channels and describes toll-free service as having unlimited channels, but the public pages do not establish one account's active concurrency, calls-per-second, burst, queueing or abuse controls. Unlimited minutes and unlimited channels are different from an enforceable call-start rate.
Emergency calling
Not verifiedDIDforSale says its phone numbers support E911 and the pricing page lists E911 among number options, but the reviewed pages do not define activation, validated-location workflow, callback, number eligibility, nomadic use or an approved test procedure. Obtain written account and location requirements for every operating site before relying on the route.
Pricing model
DocumentedDIDforSale publishes pay-as-you-go, channel-based inbound, toll-free, messaging and unlimited-use examples with tiered commitments. Displayed figures are dated public list prices, not an account quote. Preserve direction, number and channel fees, destination rates, billing increment, acceptable-use terms, commitment, taxes and renewal conditions.
Administration and support
DocumentedThe self-service portal manages interconnection records, numbers, routing, billing and CDRs, while the service page offers setup support. Public uptime and redundancy claims do not define the account's SLA exclusions, credits or response targets. Retain the governing terms, applied configuration, redacted trace and provider case together.
SMS and MMS
Not verifiedThe pricing page says local and toll-free numbers can be SMS/MMS enabled and publishes separate message rates. A voice-capable number or SIP trunk does not establish messaging activation, campaign registration, sender approval, consent, API behavior, throughput or deliverability. Verify the exact number and messaging program independently.
Build and filter inbound delivery independently
The IP-interconnection guide says an approved IP or FQDN can receive local and toll-free calls and publishes multiple inbound gateway addresses. It specifically warns that accepting only part of that provider set can make some inbound calls fail. Preserve the exact number route, customer destination, all current provider sources, delivered called-party format and PBX context.
Several provider ingress addresses support load balance and uptime, but the reviewed pages do not define customer destination priority, health checks, timeout, retry order or established-call survival. A complete firewall allowlist is not an inbound failover design. Obtain the exact customer-routing policy and test each approved failure and restoration path without broadening access beyond the published sources.
Qualify codecs, DTMF and protection on the actual call
The current product page lists G.711, G.729, u-law and A-law. Treat that list as a service capability statement, not proof of availability on every destination, licensing, payload selection, DTMF mode or transcoding. Capture the offer, answer, negotiated payloads and media endpoints for representative inbound and outbound routes.
Source-IP authorization protects an account boundary but does not encrypt signaling or media. The reviewed public pages do not establish a trunk-specific TLS, certificate-validation or SRTP procedure. Obtain the supported transports, server names, trust chain, media profiles and downgrade policy in writing, then verify the negotiated customer-facing leg. Encryption on that leg would not establish protection through the public telephone network.
Keep fax, resilience and capacity unresolved until accepted
The reviewed trunk pages do not establish T.38, fallback rules or route-specific fax behavior. Separate fax-by-email references and PBX interoperability listings do not prove that this customer trunk negotiates T.38 or carries in-band fax reliably. Qualify the exact number, direction, gateway, codec policy and approved document set.
DIDforSale prices some inbound plans by simultaneous-call channels and describes toll-free service as having unlimited channels, but public pages do not establish one account's concurrency, calls-per-second, burst, queueing or abuse controls. Unlimited minutes and unlimited channels are different from call-start capacity. Capture the active account limits and governing SLA terms before any bounded load or recovery test.
Snapshot number, price and messaging conditions
DIDforSale advertises local and toll-free numbers across more than 13,000 US and Canadian rate centers plus porting. Inventory, portability, activation, identity documents, caller-ID rights and features remain number-, account- and date-specific. Preserve the ordering result and porting requirements for each production number.
The pricing page publishes pay-as-you-go, channel-based, toll-free, messaging and unlimited-use examples with tiered commitments. Treat those as dated public list prices rather than an account quote. Retain direction, number and channel fees, destination rates, billing increment, acceptable-use rules, commitment, taxes and renewal terms. SMS/MMS enablement is a separate workflow; verify number eligibility, campaign registration, consent, API behavior, throughput and fees independently.
Resolve E911 and prove the complete service path
The service page says DIDforSale numbers support E911 and the pricing page lists E911 among number options, but the reviewed material does not define activation, validated-location workflow, callback, eligible numbers, nomadic use or an approved test procedure. Obtain written requirements for every site and calling identity, retain an independent fallback and coordinate any emergency test with the provider and local authority.
Pilot the selected authentication model, inbound and outbound identity, number format, codec and DTMF behavior, gateway filtering, failure and restoration, emergency treatment, support escalation and every required route separately. No DIDforSale account, trunk, registration, number, call, codec, fax, encryption, failover, capacity, emergency call, message, price, availability or support response was tested for this guide.
Sources & applicability
Primary references for the technical details above. Operational examples and planning checklists are VoIP.info editorial guidance.
- DIDforSale SIP trunk service ↗
- DIDforSale SIP trunk pricing ↗
- DIDforSale products overview ↗
- DIDforSale SIP interconnection guide ↗
- DIDforSale IP interconnection configuration ↗
- DIDforSale SIP account creation ↗
Examples require adaptation to your topology. No live PBX or hardware testing is claimed.