Microsoft Teams Direct Routing
Managed SBC-as-a-Service. The standard alternative to Microsoft Calling Plans for Singapore users.
See Teams DR →
Singapore · IMDA
SIP Trunk in Singapore — all-Singapore (no area codes) Inbound + Outbound
A Singapore SIP trunk with real +65 Singapore DIDs, IMDA-compliant allocation, Singapore + Tokyo ingress POPs, TLS:5061 with SRTP, every standard PBX integration. From $10.00/mo per DID plus per-minute usage, activation in 1-3 business days after KYC.
Real Singapore DIDs allocated through licensed carriers
TLS + SRTP end-to-end
5–200 channel scale per trunk
1. What a SIP trunk in Singapore actually is
A SIP trunk is the IP delivery pipe between a carrier and your PBX, AI voice agent, or call-control platform; signaling over SIP, audio over RTP. A Singapore SIP trunk is the same thing carrying +65 Singapore DIDs allocated under IMDA.
DIDHub provides the trunk authentication and SIP transport; IMDA-compliant number allocation is coordinated through our in-region carrier partners. Your PBX or platform sees a standard SIP trunk; we handle the regulator-side paperwork.
2. Singapore regulation: IMDA, KYC, compliance
IMDA requires KYC documentation before any Singapore DID can be allocated. Activation typically takes 1-3 business days. DIDHub handles the document submission and regulator coordination on your behalf.
What people typically use a Singapore SIP trunk for:
- APAC regional HQ presence, Singapore is the standard APAC headquarters for international companies.
- Banking and finance, Singapore is APAC's financial center; +65 numbers signal credibility.
- Shipping and logistics, Singapore is the world's busiest transshipment port.
- SaaS targeting APAC, Singaporean buyers expect local Caller IDs.
- Toll-free 800/1800, free for Singaporean callers, standard for premium customer service.
Singapore's regulator IMDA (Infocomm Media Development Authority) requires KYC, Singapore business registration (UEN) for companies, or verified ID for individuals, plus a Singapore address. Foreign companies typically register through a Singapore subsidiary or local registered agent. DIDHub manages the paperwork. Activation completes in 1-3 business days.
For the broader picture across countries, see our guide to international DID compliance & KYC bundles. For the SIP-trunk concept end-to-end, see the DID Number Provider guide.
3. Number types you can route over the trunk
DIDHub supports the standard Singapore number types over the SIP trunk:
| Code | Type | National dialing | International dialing | Mobile | From |
|---|---|---|---|---|---|
6 | Landline (national) | 6 XXXX XXXX | +65 6 XXXX XXXX | Yes | $10.00/mo + usage |
8, 9 | Mobile | 8 XXXX XXXX | +65 8 XXXX XXXX | Yes | $16.00/mo + usage |
800 | Toll-free | 800 XXXX XXXX | +65 800 XXXX XXXX | Yes | $30.00/mo + usage |
1800 | Toll-free | 1800 XXXX XXXX | +65 1800 XXXX XXXX | Yes | $30.00/mo + usage |
For a deeper look at how number types differ globally, see DID number types explained.
4. How DIDHub's SIP trunk works in Singapore
The technical surface of the trunk is standardised; the Singapore-specific choices are the POP, the codec list, and the failover topology.
Ingress POPs
- Singapore (primary), lowest in-region latency to Singapore endpoints.
- Tokyo (failover), secondary route used if the primary path degrades.
Transport & security
- TLS:5061 recommended for any production trunk; UDP allowed for legacy.
- SRTP for media via DTLS-SRTP or SDES.
- SIP authentication: digest registration (PBX behind NAT) or IP-ACL (static peering). See SIP authentication.
Codecs
- G.711 a-law (PCMA), the APAC default.
- G.722, wideband HD voice on capable endpoints.
- Opus, for AI voice agents and IP-native softphones.
- G.729, available on request.
For the codec deep-dive, see voice codecs explained.
DTMF
- RFC 4733 (telephone-events over RTP) is the default. SIP INFO and in-band DTMF available for legacy interop on request.
Channel concurrency
- Trunks start at 5 concurrent channels and scale to 200 per trunk off the shelf. Larger requires a custom arrangement.
- Channels are independent of DID count; you can carry 200 numbers on a 10-channel trunk if your concurrent-call peak is 10. See multiple concurrent calls on one DID.
STIR/SHAKEN
- Not applicable. STIR/SHAKEN is a US/Canada construct that doesn't exist in APAC. Trust signals come through national regulator registration and operator-side caller-ID validation.
5. Outbound calling from your Singapore trunk
Outbound from a Singapore-allocated DID to Singapore destinations is allowed within approved use cases. The per-minute economics:
| Destination | Per-minute | Billing increment | Notes |
|---|---|---|---|
| Singapore landline (geographic) | $0.05/min | 1+1 second | Standard use cases |
| Singapore mobile | $0.10/min | 1+1 second | Standard use cases |
| International from Singapore DID | Per destination rate | 1+1 second | See global rates |
Outbound caller-ID rules
- Your outbound CLI must match a DID you've allocated through the trunk. Setting an arbitrary caller ID is rejected at the SBC.
- Origin-based rating (OBR) applies on cross-border outbound, the regulated EEA tier may apply depending on the source carrier.
- For multi-region operators, see origin-based rating savings.
6. Setup in 6 steps
Sign up & submit details
Create a DIDHub account, supply your business details and the intended use case for Singapore numbers.
IMDA compliance review
We coordinate with IMDA and our in-region carrier; typical timeline 1-3 business days.
Allocate DIDs & channel capacity
You pick the Singapore number types you need and how many. Channel capacity allocated at the same time.
Receive trunk credentials
SIP URI (defaults to sip.didhub.io, terminating to Singapore), digest username/password or IP-ACL details, TLS cert verification fingerprint, and your assigned DIDs.
Wire up your PBX or platform
Standard SIP trunk configuration on Asterisk, FreePBX, 3CX, Kamailio, OpenSIPS, or any modern stack. For Teams Direct Routing, Vapi, Retell, or other BYOC platforms, paste credentials into their BYOC config.
Test inbound + outbound
Place a test call to one of your DIDs from a Singapore mobile or landline; place a test outbound back. Confirm caller-ID resolves correctly, codec negotiates as expected, and audio quality is acceptable.
Asterisk pjsip example
; /etc/asterisk/pjsip.conf [transport-tls] type=transport protocol=tls bind=0.0.0.0:5061 cert_file=/etc/asterisk/keys/asterisk.crt priv_key_file=/etc/asterisk/keys/asterisk.key method=tlsv1_2 [didhub-singapore] type=auth auth_type=userpass username=YOUR_DIDHUB_USERNAME password=YOUR_DIDHUB_PASSWORD [didhub-singapore] type=aor contact=sip:sip.didhub.io:5061;transport=tls qualify_frequency=30 [didhub-singapore] type=endpoint transport=transport-tls context=from-didhub disallow=all allow=g711a,g722,opus outbound_auth=didhub-singapore aors=didhub-singapore dtmf_mode=rfc4733 media_encryption=sdes direct_media=no
3CX SIP trunk template snapshot
# 3CX -> SIP Trunks -> Add SIP Trunk -> Generic SIP Trunk Trunk name: DIDHub Singapore Registrar: sip.didhub.io Transport: TLS Port: 5061 Authentication: Register/Account based Auth ID: YOUR_DIDHUB_USERNAME Auth password: YOUR_DIDHUB_PASSWORD Outbound caller ID: +65 ... (one of your allocated DIDs) Codecs (priority): G.711a / G.722 / Opus
7. Integration patterns
Every modern PBX, UC platform, and AI voice stack can authenticate against the trunk:
Asterisk / FreePBX
Standard pjsip trunk config (snippet below). FreePBX trunk module maps cleanly to DIDHub's IP-ACL or registration modes.
Asterisk → · FreePBX →3CX
Generic SIP trunk template with TLS:5061. Outbound caller ID per extension; per-DID inbound routing rules.
3CX guide →AI voice agents (Vapi, Retell, ElevenLabs)
BYOC SIP trunk with Singapore ingress for tight latency. Bind specific Singapore DIDs to specific agents.
AI voice integrations →Kamailio / OpenSIPS
Per-trunk DNID auto-correct, SRV-based POP failover (Singapore primary / Tokyo failover).
Kamailio →Softphones (Zoiper, Bria, Linphone)
Per-extension digest registration; useful for distributed support teams routing Singapore DIDs to remote agents.
Softphones →Start your Singapore SIP trunk today
Live in 1-3 business days. Real Singapore DIDs, no setup fee after KYC, no contract.
8. Pricing
Four line items: per-DID monthly rental, per-minute inbound usage on every Singapore DID (even landline geographic numbers carry an inbound MOU charge in Singapore), channel capacity, and per-minute outbound. Setup is $0 once IMDA paperwork is approved.
Per-DID monthly
| Type | From | Notes |
|---|---|---|
| Geographic (Singapore city codes) | $10.00/mo + usage | Inbound per-minute applies; standard use cases |
| Non-geographic / national | $40.00/mo + usage | Subject to regulator allocation |
| Toll-free | $30.00/mo + usage | Free for callers; you pay inbound per-minute |
Channel capacity
| Channels | Monthly | Suited for |
|---|---|---|
| 5 | Included with first DID | SMB / single office |
| 25 | $95/mo | Small contact centre, AI agent low concurrency |
| 50 | $180/mo | Mid-size contact centre, AI agent medium concurrency |
| 100 | $330/mo | Large contact centre, multi-tenant SaaS |
| 200 | $580/mo | Enterprise; larger by arrangement |
Per-minute outbound
See section 5 above and the full global rate sheet.
9. Porting an existing Singapore number
Existing Singapore number? Porting timeline is 2-3 weeks.
- Typical port time: 2-3 weeks
- Required documents: phone bill + LOA + ID + proof of address (IMDA requirements)
- Cost: port-in fee per number; carrier-side fees may apply
For the full porting playbook (US/UK/EU + the global gotchas), see number porting explained.
10. FAQ
Which POP should I connect to for a Singapore SIP trunk?
Singapore is the recommended primary; Tokyo is the standard failover. Both terminate to Singapore via in-region carriers.
How long does activation take for a Singapore SIP trunk?
1-3 business days after KYC documents are accepted (or instantly where KYC isn't required). Provisioning the SIP side itself is hours, not days; the variability is on the IMDA/carrier side.
What codecs should I configure for a Singapore SIP trunk?
G.711a / G.722 / Opus as the negotiation list, in that order. G.711a is the regional default for Singapore interop.
Can I use my Singapore SIP trunk with Microsoft Teams?
Yes, via Microsoft Teams Direct Routing through DIDHub's managed SBC. See Teams Direct Routing.
Can I use my Singapore SIP trunk with AI voice agents (Vapi, Retell, ElevenLabs)?
Yes, BYOC SIP trunk works with every major AI voice platform. Bind specific Singapore DIDs to specific agents; outbound CLI must match an allocated DID.
How many concurrent calls can one Singapore DID handle?
The DID is an address; concurrent-call capacity is set by the channel count on the trunk. A 50-channel trunk with 1 DID can carry 50 concurrent calls to that one number; the same trunk with 200 DIDs can carry 50 concurrent calls across any combination of those numbers.
Does STIR/SHAKEN apply in Singapore?
N/A (regional construct). Trust signals come instead through national regulator registration and operator-side caller-ID validation.
Can I port my existing Singapore number to a DIDHub SIP trunk?
Yes. Typical Singapore port timeline is 2-3 weeks. Required documents vary by number type; contact us for the specific checklist. See number porting explained for the global picture.
What use cases get approved most easily?
Customer service inbound, opted-in callbacks, transactional 2FA, inbound AI voice agents, and Microsoft Teams Direct Routing for registered entities. Cold outbound, unsolicited SMS campaigns, and anonymous-relay setups are routinely rejected.
Start your Singapore SIP trunk today
Live in 1-3 business days. Real Singapore DIDs, every standard PBX and AI-voice integration, no setup fee after KYC, no contract.