SIP Trunk in Sri Lanka — Colombo, Kandy or Galle Inbound + Outbound

1. What a SIP trunk in Sri Lanka 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 Sri Lanka SIP trunk is the same thing carrying +94 Sri Lanka DIDs allocated under TRCSL.

DIDHub provides the trunk authentication and SIP transport; TRCSL-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. Sri Lanka regulation: TRCSL, KYC, compliance

TRCSL requires KYC documentation before any Sri Lanka DID can be allocated. Activation typically takes 5-10 business days. DIDHub handles the document submission and regulator coordination on your behalf.

What people typically use a Sri Lanka SIP trunk for:

• Sri Lanka market presence, Colombo 11 for B2B credibility.
• Tourism inbound, Colombo, Kandy, Galle, Sigiriya; local numbers convert better.
• IT services and outsourcing, Sri Lanka has a growing IT services sector.
• Diaspora communications, large Sri Lankan diaspora in UK, Canada, Australia.
• Toll-free 0800, free for Sri Lankan callers, standard for support.

Sri Lanka's regulator TRCSL requires light KYC for foreign customers, incorporation documents and an authorized contact. Activation 5-10 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 Sri Lanka number types over the SIP trunk:

For a deeper look at how number types differ globally, see DID number types explained.

4. How DIDHub's SIP trunk works in Sri Lanka

The technical surface of the trunk is standardised; the Sri Lanka-specific choices are the POP, the codec list, and the failover topology.

Ingress POPs

• Singapore (primary), lowest in-region latency to Sri Lanka endpoints.
• Dubai (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 Sri Lanka trunk

Outbound from a Sri Lanka-allocated DID to Sri Lanka destinations is allowed within approved use cases. The per-minute economics:

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

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-sri-lanka]
type=auth
auth_type=userpass
username=YOUR_DIDHUB_USERNAME
password=YOUR_DIDHUB_PASSWORD

[didhub-sri-lanka]
type=aor
contact=sip:sip.didhub.io:5061;transport=tls
qualify_frequency=30

[didhub-sri-lanka]
type=endpoint
transport=transport-tls
context=from-didhub
disallow=all
allow=g711a,g722,opus
outbound_auth=didhub-sri-lanka
aors=didhub-sri-lanka
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 Sri Lanka
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: +94 ... (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:

8. Pricing

Four line items: per-DID monthly rental, per-minute inbound usage on every Sri Lanka DID (even landline geographic numbers carry an inbound MOU charge in Sri Lanka), channel capacity, and per-minute outbound. Setup is $0 once TRCSL paperwork is approved.

Per-DID monthly

Channel capacity

Per-minute outbound

See section 5 above and the full global rate sheet.

9. Porting an existing Sri Lanka number

Existing Sri Lanka number? Porting timeline is 3-5 weeks.

• Typical port time: 3-5 weeks
• Required documents: phone bill + LOA + ID + proof of address (TRCSL 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 Sri Lanka SIP trunk?

Singapore is the recommended primary; Dubai is the standard failover. Both terminate to Sri Lanka via in-region carriers.

How long does activation take for a Sri Lanka SIP trunk?

5-10 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 TRCSL/carrier side.

What codecs should I configure for a Sri Lanka SIP trunk?

G.711a / G.722 / Opus as the negotiation list, in that order. G.711a is the regional default for Sri Lanka interop.

Can I use my Sri Lanka SIP trunk with Microsoft Teams?

Yes, via Microsoft Teams Direct Routing through DIDHub's managed SBC. See Teams Direct Routing.

Can I use my Sri Lanka SIP trunk with AI voice agents (Vapi, Retell, ElevenLabs)?

Yes, BYOC SIP trunk works with every major AI voice platform. Bind specific Sri Lanka DIDs to specific agents; outbound CLI must match an allocated DID.

How many concurrent calls can one Sri Lanka 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 Sri Lanka?

N/A (regional construct). Trust signals come instead through national regulator registration and operator-side caller-ID validation.

Can I port my existing Sri Lanka number to a DIDHub SIP trunk?

Yes. Typical Sri Lanka port timeline is 3-5 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.

11. Related country pages