SRV, which is an abbreviation for Service, is a DNS record, which permits you to employ a domain name for a certain service different from a website. By setting up a few SRV records, you will be able to use the domain name with different providers and direct it to a number of servers at a time, every single server managing a different service. You can specify the port number for the connection to each machine, so there won't be any interference. You could also set individual priorities and weight for 2 records which are employed for the same service, but point to different servers for redundancy or load balancing. Using an SRV record you can employ your domain address or a subdomain under it for a Voice-Over-IP server, for example, and have the actual software running on several machines with different companies. Which one a client of yours is going to use depends on the priority and weight values that you have set.