STIR/SHAKEN Identity Header Decoder (PASSporT)
Decode a SIP Identity header or PASSporT: attestation A/B/C, orig and dest numbers, iat age, origid and certificate URL. No signature check.
October 6, 2026
How Many SIP Channels Do You Need? Size SIP Trunks with Erlang B
Size SIP trunks properly: measure busy-hour traffic from your PBX CDR, convert it to Erlangs, choose channels with Erlang B for a 1% grade of service, then check bandwidth and set the channel limit on the PBX.
October 3, 2026
SIP Error Codes on Asterisk and FreePBX: Fix 403, 404, 408, 488 and 503
A troubleshooting walk-through for the SIP errors that break calls on Asterisk, FreePBX and SIP trunks: how to find the failing response, then what causes 403, 404, 408, 480, 488 and 503 and how to fix each.
October 3, 2026
VoIP MOS Calculator: Call Quality (R-Factor) from Latency, Jitter and Packet Loss
Estimate the MOS and R-factor of VoIP calls from latency, jitter, packet loss and codec with the ITU-T G.107 E-model, see where the score is lost, and how much loss or delay your network can take.
October 3, 2026
Erlang Calculator: How Many SIP Channels (Erlang B) or Call Centre Agents (Erlang C)
Work out how many SIP channels or trunks you need for a target blocking rate (Erlang B), or how many agents a call centre needs for a service level (Erlang C), from busy-hour calls and average call length.
October 3, 2026
SIP Trace Analyzer: Find NAT, Codec and Dropped-Call Problems in a SIP Log
Paste a SIP trace from sngrep, pjsip set logger, sip set debug or tcpdump and get the call flow, codecs, media addresses and the likely cause of one-way audio, 32-second drops, failed registrations and codec errors.
October 3, 2026
SIP Response Codes: Lookup for Every SIP Error, With Causes and Fixes
Look up any SIP response code (403, 404, 408, 480, 486, 488, 503 and more) or Q.850 hangup cause and see what it means, the usual causes on Asterisk, FreePBX and SIP trunks, and what to check.
October 3, 2026
VoIP Bandwidth Calculator: Per-Call and Total Bandwidth by Codec
Works out how much upload and download a number of concurrent calls needs for a given codec, packet interval, IP version, SRTP and VPN tunnel, with a byte-by-byte breakdown.
September 30, 2026
SIP SRV Checker: Free NAPTR, SRV and SIP TLS Test
Checks the DNS records SIP phones and trunks use to find your server: NAPTR transport preference, SRV records for UDP, TCP and TLS, and whether every target resolves correctly.
September 30, 2026
JustCall vs CloudTalk: Best Cloud Phone System in 2026 Compared
JustCall and CloudTalk compared on price, minimum licences, calling allowances, number coverage, integrations, dialers and AI. JustCall suits CRM-driven teams of two or more; CloudTalk suits routing-heavy teams, single users and multi-country numbers.
September 30, 2026
CloudTalk Review: Best Value Call Center Software for Small Teams?
A cloud call center and business phone system with call queues and IVR on every plan, local numbers in 160+ countries and a one-licence minimum on the lower tiers. Integrations start on Essential, and dialers and AI are mostly add-ons.
September 30, 2026
JustCall Review: Best Cloud Phone System for CRM Teams?
A cloud phone system built around CRM integrations and AI call analysis. Strong for sales and support teams on HubSpot, Salesforce or Pipedrive; the two-licence minimum and AI features locked to higher tiers matter for small offices.
September 30, 2026