SRV, which is an abbreviation for Service, is a DNS record, which enables you to employ a domain for a specific service different from a website. By setting up a couple of SRV records, you’ll be able to use the domain name with different providers and forward it to numerous servers at once, every single server handling a separate service. You'll be able to specify the port number for the connection to each machine, so there will not be any interference. You can even set different priorities and weight for two records which are employed for the same service, but point to different servers for redundancy or load balancing. Using an SRV record you can use your domain 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 will depend on the priority and weight values you have set.