Start with the no-REGISTER service boundary
LoopUp documents an IP-to-IP service for dedicated customer endpoints and explicitly says registration is unsupported. Record the legal account, trunk name, immutable region, assigned numbers, channel limit, protocol, primary endpoint, additional endpoints, PBX or SBC, sites and support owner.
Do not add registrar, expiry or digest settings from a generic trunk wizard. A reachable address, OPTIONS response, TLS handshake and accepted call are separate milestones.
Documented service facts
Reviewed 2026-10-14. Compare SIP trunk services →
SIP authentication
DocumentedLoopUp documents IP-to-IP SIP trunks with dedicated customer endpoints. Its encrypted AudioCodes and Ribbon examples require a customer public certificate, an approved issuing root and mutual TLS. The reviewed public pages do not define digest credentials or a complete authorization policy for the UDP and TCP variants. Preserve the selected endpoint, public address or FQDN, certificate identity, trust anchors and current order rather than turning reachability into authorization.
SIP registration
DocumentedThe August 2026 setup guide says SIP registration is not supported. This is an IP-to-IP trunk using dedicated, globally unique endpoint-and-port combinations. Do not configure a registrar, expiry, contact refresh or digest registration from a generic PBX template; retain the issued regional targets and customer endpoint instead.
Inbound delivery and number format
DocumentedNumbers are assigned to a trunk in the LoopUp portal. The trunk region must match the region of the numbers, and LoopUp requires E.164 presentation. The public guide does not establish one account's assigned numbers, inbound Request-URI, asserted identity, diversion history or PBX destination. Preserve an authorized INVITE and first matching PBX rule before normalizing digits.
Additional endpoints and regional edges
DocumentedLoopUp lets the administrator choose round-robin distribution or ordered failover across a primary and optional additional customer endpoints. It also publishes regional platform endpoints and recommends DNS because addresses can change. The reviewed pages do not define every health signal, response class, retry timer, established-call survival or restoration interval. Prove each new-call path in a provider-approved window.
Regions and number eligibility
Not verifiedThe setup guide publishes AMER, EMEA, APAC and South Africa platform regions and requires a trunk's region to match its numbers. It does not provide a complete current country inventory, number availability, local-address rule, portability matrix or activation schedule for one order. Confirm each number and market in dated account documentation.
Audio codecs, ports and DTMF
DocumentedLoopUp lists PCMA and PCMU and UDP media ports 7000-65535. The reviewed setup material does not publish a DTMF method, packetization rule, silence-suppression policy or selected account result. Retain both SDP bodies, payload mapping, media addresses, packet directions and digit evidence for an authorized call.
Fax and T.38
DocumentedThe setup guide lists T.38, and the current Ribbon example creates a T.38 media profile. These are capability and configuration references, not evidence that one account permits T.38, a call renegotiated, UDPTL crossed every firewall or a document arrived correctly. Preserve the re-INVITE, SDP, packet path, gateway settings and permitted received document.
Signaling and media protection
DocumentedLoopUp offers UDP, TCP or TLS signaling; the setup workflow couples its TLS selection with encrypted media and publishes signaling and SRTP cipher lists. Its SBC guides use TLS on 5061, customer certificates, approved roots, LoopUp's public chain and mutual authentication. Treat configured TLS, a successful handshake, negotiated SIP, SDP protection attributes and observed SRTP as separate evidence, and do not project this protection beyond the LoopUp-facing leg.
- LoopUp SIP Trunking Setup Guide ↗
- LoopUp SIP Trunking Public Certificate Chain ↗
- LoopUp SIP Trunking Supported Root Certificate Authorities ↗
- LoopUp SIP Trunking Configuration for AudioCodes Mediant SBCs ↗
- LoopUp SIP Trunking Configuration for Ribbon 1000, 2000, and SWe Edge SBCs ↗
- RFC 5246: TLS 1.2 ↗
- RFC 4568: SDP Security Descriptions for Media Streams ↗
Channel limit and call starts
DocumentedThe self-service form requires a channel limit from 1 through 100 and directs larger requests to support. That field is not a calls-per-second allowance, burst policy, PBX ceiling, bandwidth result or measured concurrency. Preserve the signed channel quantity, directions, number assignment, access capacity and observed rejection separately.
Emergency calling
Not verifiedThe reviewed public trunk, certificate and SBC pages do not establish emergency-call eligibility, registered location, callback identity, nomadic restrictions, dispatch behavior or an approved validation method. Obtain the current service schedule for every number, maintain an accessible independent path and never place an uncoordinated emergency call.
Pricing and commercial terms
Not verifiedThe reviewed public pages do not publish a complete order-ready price for channels, numbers, ports, calls, certificates, support, taxes or term. Use a dated quote and service schedule; do not convert the self-service 1-to-100 channel control into pricing or availability.
Portal, DNS and support ownership
DocumentedThe portal creates, edits and deletes trunks, assigns numbers and records primary and additional endpoints. LoopUp recommends using its published DNS names because platform addresses can change. The reviewed pages do not establish an account's administrator scope, support entitlement, SLA response, maintenance process or restoration result. Preserve named owners, current configuration export and escalation contacts.
SMS and MMS
Not verifiedThe reviewed SIP trunk, certificate and SBC pages do not establish SMS or MMS support on assigned numbers. Confirm eligibility, sender registration, API or portal path, inbound routing, throughput, retention, compliance and price as a separate service.
Match number region, E.164 identity and PBX route
The trunk region must match the numbers assigned in the portal, and LoopUp requires E.164 presentation. Its guide also requires P-Asserted-Identity on messages sent to LoopUp, including anonymous calling. Preserve the assigned number, Request-URI, From, P-Asserted-Identity, privacy fields and first PBX rule on both directions.
A number visible in the portal is not proof of activation, inventory, portability, inbound delivery, emergency location or caller-identity acceptance.
Choose endpoint distribution as a call-routing policy
Round robin gives configured customer endpoints equal weighting, while failover tries them in order for each new inbound call. Keep that provider-side policy separate from DNS resolution of LoopUp's own regional endpoints, PBX trunk sequence, WAN failover and established-dialog behavior.
In an approved window, prove first choice, qualifying failure, next endpoint, PBX acceptance and restoration. Do not infer health checks or exact timers that the reviewed public pages do not publish.
Treat mutual TLS as several verifiable objects
For encrypted trunks, the current SBC guides require a customer public certificate rooted in LoopUp's approved list, trust for LoopUp's published chain, an FQDN and mutual TLS. Preserve the configured name, certificate subject and SANs, issuer chain, validity, key custody, trust stores, TLS profile and observed peer identity.
A certificate file that imports successfully does not prove the selected trunk uses it or that the peer accepts it. Use the focused TLS and secure-media diagnostic before replacing unrelated routing settings.
Verify SIP protection and media protection separately
LoopUp publishes signaling cipher and SRTP cipher lists and couples TLS trunk selection with encrypted media. Confirm the actual signaling connection, certificate exchange, SIP request, SDP security attributes, negotiated suite and packets on the LoopUp-facing leg.
TLS protects signaling transport; SRTP protects media under its negotiated keying method. Neither statement proves protection on another carrier, PBX, recording, transfer or endpoint leg.
Close codec, fax, capacity and service unknowns
The public guide lists PCMA, PCMU, T.38, media ports and a self-service channel range of 1 through 100. Validate codec and fax negotiation, two-way media, digits, document result and concurrency without converting a feature list into an interoperability or load claim.
Obtain current account documents for coverage, number eligibility, emergency service, messaging, pricing, support and maintenance. No LoopUp service, certificate, endpoint, packet or call was tested for this article.
Sources & applicability
Primary references for the technical details above. Operational examples and planning checklists are VoIP.info editorial guidance.
- LoopUp SIP Trunking Setup Guide ↗
- LoopUp SIP Trunking Public Certificate Chain ↗
- LoopUp SIP Trunking Supported Root Certificate Authorities ↗
- LoopUp SIP Trunking Configuration for AudioCodes Mediant SBCs ↗
- LoopUp SIP Trunking Configuration for Ribbon 1000, 2000, and SWe Edge SBCs ↗
- RFC 5246: TLS 1.2 ↗
- RFC 4568: SDP Security Descriptions for Media Streams ↗
Examples require adaptation to your topology. No live PBX or hardware testing is claimed.