Five platforms. One C ABI. Every binding printed from it.

import Sipral

let stack = try SipralStack(bindHost: "192.0.2.10")
let account = try stack.addAccount(
    aor: "sip:alice@example.invalid",
    registrarAddress: "203.0.113.10:5060",
    registrar: "sip:example.invalid",
    authUser: "alice",
    authPassword: secret
)
try account.register()

// Without `registrar` the account never registers: registering throws, and
// the registrar address is only the outbound proxy. Left out, `bindHost` and
// `mediaHost` are the address of the route toward the registrar.

let call = try stack.placeCall(account: account, target: "sip:bob@example.invalid", mediaHost: "192.0.2.10")
let events = call.events()                 // take it at once: nothing earlier is replayed
for await event in events {
    if event.kind == .mediaStarted { break }
}
// the microphone and the loudspeaker are the library's from here on: the
// stack is in device mode, and the call is heard without a line of audio code

try call.hold()
try call.resume()
try call.sendDtmf("123#")
try call.transfer(to: "sip:carol@example.invalid")   // blind: .transferDone's transferData says how it went
try call.hangup(reason: .normalClearing)   // or hangup(), with no Reason
call.close()