SIP trunking provides PSTN connectivity for contact centers and PBX systems through IP-based voice channels — replacing legacy ISDN and analog circuits with flexible, software-defined telephony connections that scale with demand and typically reduce per-minute costs. The right SIP trunk configuration is foundational to contact center voice quality and reliability.
SIP trunking vendor selection is more nuanced than it appears — pricing models, codec support, geographic coverage, redundancy architecture, and technical support quality vary significantly across carriers. Organizations migrating from TDM circuits to SIP, deploying cloud voice over existing infrastructure, or optimizing their current SIP trunk costs all benefit from independent assessment. RLM advises on SIP trunk architecture, vendor selection, and cost optimization.
A structured advisory process — from discovery and market evaluation to vendor selection and post-deployment optimization — tailored to your specific environment and objectives.
We assess your current SIP trunk environment — documenting concurrent call capacity, carrier pricing, quality metrics, geographic coverage, and the configuration gaps that affect voice quality or resilience.
We evaluate SIP trunk providers — Bandwidth, Twilio, Lumen, Vonage, Verizon, AT&T — against your geographic requirements, call volume, codec preferences, and the redundancy design that achieves your RTO for voice service.
We design the SIP trunk architecture — Session Border Controller selection, failover configuration, codec negotiation, SRTP encryption, and the quality of service configuration that prioritizes voice traffic.
We benchmark your current SIP trunk pricing against market rates and design the carrier mix and traffic distribution that minimizes per-minute costs while maintaining geographic redundancy.
These are the dimensions that consistently separate successful CX deployments from costly ones — and the questions RLM will help you answer before any commitment.
SIP trunks must support the codecs used by your contact center platform and endpoints. Evaluate codec compatibility — particularly G.711 vs. G.729 trade-offs — and whether codec transcoding introduces perceptible latency.
SIP trunk providers participate in STIR/SHAKEN call authentication at different attestation levels. Evaluate full attestation support and the impact on outbound call answer rates.
SIP trunks must support E911 with accurate location information. Evaluate E911 routing architecture — particularly for distributed and remote locations — and the carrier's E911 compliance approach.
Voice service continuity requires carrier-level redundancy. Evaluate primary/secondary carrier failover, detection time for failover triggering, and the call-in-progress handling during failover events.
Migrating to a new SIP trunk carrier requires porting existing numbers. Evaluate porting processes, timelines, and the parallel operation approach that prevents number availability gaps during cutover.
"RLM helped us select and implement the right CCaaS platform in half the time it would have taken us on our own. Their vendor knowledge is unmatched — they knew exactly what questions to ask."
"We had a legacy premise system and 90 days to migrate. RLM built the plan, managed the vendors, and we hit the deadline with zero customer disruption."
Talk to an RLM advisor who specializes in CX technology. We'll help you find the right solution for your business — without vendor bias.