At first glance Nexmo isn’t exactly what you’d think of as a next-generation technology company. It traffics in old-school telecom signaling protocols like SS7, but in doing so it’s able to link the app-centric world of IP communications with mobile networks — no matter how old — around the world. Like its competitor Twilio, Nexmo can give developers access to services like SMS that would normally be locked inside carriers’ labyrinth networks, and through its network of relationships with the carriers it can streamline the transaction process.

Based jointly in San Francisco and London, Nexmo says its current SMS API can reach 5 billion mobile devices or connections around the world. That’s only about 900 million short of the total number of non-machine-to-machine subscriptions in the world, according to the GSM Association.

The company said its next step is to expand its catalog of telco APIs, but it didn’t give any specific examples. You can bet that VoIP is probably in the mix though. Being able to establish an in-app VoIP call that can connect to any mobile phone number in the world would be a very attractive service to customers like AirBnB.

Correction: An earlier version of this post said Zendesk was an SMS customer of Nexmo. Though Zendesk is listed on Nexmo’s website as a customer, it uses Twilio for its SMS and push messaging services. Nexmo, however, has integrated its service with the Zendesk platform even though it has no direct business relationship with the company.

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