Phone numbers for Cartesia — SIP trunk setup with DIDHub
Cartesia Sonic delivers ultra-low-latency TTS for realtime voice agents. Pair with DIDHub for the PSTN side: SIP trunk + 136-country DID inventory + STIR/SHAKEN A-attestation, with regional ingress to keep the latency budget tight.
Why DIDHub for Cartesia
- Latency-tight regional ingress. Cartesia's Sonic model is built for sub-100ms TTS. The PSTN hop matters — DIDHub regional edges minimize SIP/RTP latency.
- STIR/SHAKEN A-attestation. US/CA outbound stays under mobile-carrier spam thresholds.
- Plays nicely with LiveKit / Pipecat / custom stacks. Cartesia is typically wired into a broader agent framework. DIDHub's BYOC SIP works regardless of the framework.
- Per-DID flat pricing. Predictable economics for Cartesia-based products.
BYOC setup — step by step
- Sign up at /signup and provision DIDs.
- Generate DIDHub SIP credentials.
- Configure your agent framework (LiveKit, Pipecat, custom) with DIDHub as the SIP carrier.
- Wire Cartesia Sonic into the TTS leg of your pipeline.
- Test end-to-end latency on a real call — STT → LLM → Cartesia → PSTN egress.
Caller-ID configuration
Caller-ID configuration depends on which agent framework you've wrapped Cartesia in (LiveKit, Pipecat, etc.). In all cases, the outbound From-header should be a DIDHub-allocated DID.
For US/CA outbound: DIDHub signs every call with STIR/SHAKEN attestation A on DIDHub-allocated and DIDHub-ported numbers. This is the level that mobile carriers (T-Mobile, Verizon, AT&T) treat with baseline trust — calls signed with weaker attestation are increasingly flagged as “Spam Likely” or sent straight to voicemail. See STIR/SHAKEN explained for the full background.
For non-US destinations: present a local DID as Caller-ID for best answer rates. AI agent calling a Madrid customer should present a +34 (Spanish) Caller-ID, not a US number. DIDHub serves 136 countries with dedicated landing pages so you can match Caller-ID to destination.
Latency & regional ingress
Realtime AI voice is brittle to network latency — an extra 100ms of SIP egress can break the natural-conversation feel. DIDHub operates SIP/RTP edges in:
- NOAM: Ashburn (US-East), San Jose (US-West), Dallas
- EU: Frankfurt, Amsterdam
- APAC: Singapore, Tokyo
- MENA: Dubai
Pick the edge nearest to your Cartesia inference region. Typical sub-50ms regional ingress for the closest pair. If you need a region we don't list, talk to [email protected] — we add edges in response to customer demand.
FAQ
Why Cartesia for voice agents?
Cartesia Sonic offers some of the lowest-latency TTS in the market — especially valuable for realtime conversational agents where every 100ms matters.
Does DIDHub do anything Cartesia-specific?
No — DIDHub is the carrier; Cartesia is the TTS. They compose via your agent framework.
How tight can end-to-end latency get?
Sub-1s STT + LLM + TTS + PSTN hop is achievable with regional Cartesia + regional DIDHub + a fast LLM.
Can Cartesia voice be used commercially?
Per Cartesia's TOS. DIDHub is just the telephony — voice IP and licensing are between you and Cartesia.
Provision your first Cartesia DID
Sign up at /signup, pick a country / area code, and route the DID to your Cartesia BYOC SIP trunk. $1.99/mo for a US number, sub-60-second activation on most countries. No commits.
Ready to get a number?
Pick a DID in 130+ countries from $1.99/month. Activates instantly on most numbers.