# Building On-call: The complexity of phone networks

DevFeed: [Building On-call: The complexity of phone networks](<https://devfeed.tech/articles/building-on-call-the-complexity-of-phone-networks-12002.md>)

Original publisher: [Read original article](<https://incident.io/blog/the-complexity-of-phone-networks>)

Author: Leo Sjöberg

Published: 2024-07-16T15:39:00Z

Content type: article

Language: en

Sources: [The incident.io Blog](<https://devfeed.tech/sources/the-incident-io-blog.md>)

Topics: [Networks](<https://devfeed.tech/topics/networks.md>), [API](<https://devfeed.tech/topics/api.md>), [observability](<https://devfeed.tech/topics/observability.md>)

Tags: [api](<https://devfeed.tech/tags/api.md>), [complexity](<https://devfeed.tech/tags/complexity.md>), [incident](<https://devfeed.tech/tags/incident.md>), [incident-channel](<https://devfeed.tech/tags/incident-channel.md>), [incident-management](<https://devfeed.tech/tags/incident-management.md>), [incident-response](<https://devfeed.tech/tags/incident-response.md>), [networks](<https://devfeed.tech/tags/networks.md>), [observability](<https://devfeed.tech/tags/observability.md>), [on-call](<https://devfeed.tech/tags/on-call.md>), [outage](<https://devfeed.tech/tags/outage.md>), [post-mortem](<https://devfeed.tech/tags/post-mortem.md>), [slack-incident](<https://devfeed.tech/tags/slack-incident.md>)

## AI overview

This article examines the complexity of delivering on-call SMS and phone-call notifications. It traces an escalation from an application through a telecom API provider and network partners to carriers, explaining how limited observability, inconsistent carrier behavior, misleading error codes, and toll-fraud controls make failures difficult to diagnose.

## Source excerpt

Making a phone call is easy...right? It's time to re-examine the things you thought were true about phone calls and SMS.