A system comprising: a cloud provider network including a first control plane service to manage customer compute instances hosted on resources of the cloud provider network , wherein the resources of the cloud provider network include resources deployed within the cloud provider network and resources deployed within a first communications service provider network that is a separate network from the cloud provider network ; and a first provider substrate extension of the cloud provider network , wherein the first provider substrate extension includes at least some of the resources deployed within the first communications service provider network , and wherein the first provider substrate extension : includes a first computer system having capacity for executing customer compute instances ; is controlled at least in part by the first control plane service via a connection through at least a portion of the first communications service provider network , and executes at least a first customer compute instance using the first computer system, wherein the first customer compute instance communicates with a first mobile computer system connected via the first communications service provider network , wherein the first mobile computer system is a subscriber to the first communications service provider network , and wherein the first customer compute instance communicates with the first mobile computer system without traversing a network that carries traffic of users not subscribed to the first communications service provider network . a cloud provider network including a first control plane service to manage customer compute instances hosted on resources of the cloud provider network , wherein the resources of the cloud provider network include resources deployed within the cloud provider network and resources deployed within a first communications service provider network that is a separate network from the cloud provider network ; and a first provider substrate extension of the cloud provider network , wherein the first provider substrate extension includes at least some of the resources deployed within the first communications service provider network , and wherein the first provider substrate extension : includes a first computer system having capacity for executing customer compute instances ; is controlled at least in part by the first control plane service via a connection through at least a portion of the first communications service provider network , and executes at least a first customer compute instance using the first computer system, wherein the first customer compute instance communicates with a first mobile computer system connected via the first communications service provider network , wherein the first mobile computer system is a subscriber to the first communications service provider network , and wherein the first customer compute instance communicates with the first mobile computer system without traversing a network that carries traffic of users not subscribed to the first communications service provider network . includes a first computer system having capacity for executing customer compute instances ; is controlled at least in part by the first control plane service via a connection through at least a portion of the first communications service provider network , and executes at least a first customer compute instance using the first computer system, wherein the first customer compute instance communicates with a first mobile computer system connected via the first communications service provider network , wherein the first mobile computer system is a subscriber to the first communications service provider network , and wherein the first customer compute instance communicates with the first mobile computer system without traversing a network that carries traffic of users not subscribed to the first communications service provider network . <EOS>