diff --git a/README.md b/README.md
index d89ff3d..1820f53 100644
--- a/README.md
+++ b/README.md
@@ -1,9 +1,97 @@
 # opensips_exporter
 
-Work In Progress
+This exporter exposes OpenSIPS metrics for consumption by Prometheus using the Unix socket 
+provided by OpenSIPS. It uses the 
+OpenSIPS [Management Interface](http://www.opensips.org/Documentation/Interface-MI-1-11) to gather
+these statistics.
 
-Currently, this opensips_exporter doesn't work. More documentation to come.
+Tested and developed for OpenSIPS 1.11. Though the Management Interface to gather metrics is available
+in other OpenSIPS versions.
 
+## Usage
+Make sure `$GOPATH/bin` is in your `$PATH`.
+```
+Usage of opensips_exporter:
+  -path string
+    	The path where metrics will be served (default "/metrics")
+  -port string
+    	Port on which the OpenSIPS exporter listens. (default "9737")
+  -socket string
+    	Path to the socket file for OpenSIPS. (default "/var/run/ser-fg/ser.sock")
+```
+
+## Exported Metrics
+
+| Metric | Meaning | Labels |
+| ------ | ------- | ------ |
+| opensips_core_bad_URIs_rcvd | Number of URIs that OpenSIPS failed to parse. | |
+| opensips_core_bad_msg_hdr | Number of SIP headers that OpenSIPS failed to parse. | |
+| opensips_core_replies | Number of received replies by OpenSIPS. | kind|
+| opensips_core_replies_total | Total number of received replies by OpenSIPS. | |
+| opensips_core_request | Number of requests by OpenSIPS. | kind |
+| opensips_core_requests_total | Total number of received requests by OpenSIPS. |  |
+| opensips_core_unsupported_methods | Number of non-standard methods encountered by OpenSIPS while parsing SIP methods. | |
+| opensips_core_uptime_seconds | Number of seconds elapsed from OpenSIPS starting. | |
+| opensips_dialog_dialogs | Number of dialogs. | status |
+| opensips_dialog_received | The number of dialog events received from other OpenSIPS instances. | event |
+| opensips_dialog_sent | Number of replicated dialog requests send to other OpenSIPS instances. | event |
+| opensips_load_load | Percentage of UDP children that are awake and processing SIP messages on the specific UDP interface. |ip, port, protocol|
+| opensips_load_tcp_load | Percentage of TCP children that are awake and processing SIP messages. | | 
+| opensips_net_waiting | Number of bytes waiting to be consumed on an interface that OpenSIPS is listening on. | protocol |
+| opensips_pkmem_fragments | Currently available number of free fragments in the private memory for OpenSIPS process. | pid |
+| opensips_pkmem_free_size | Free private memory available for the OpenSIPS process. Computed as total_size - real_used_size. | pid |
+| opensips_pkmem_max_used_size | The maximum amount of private memory ever used by the OpenSIPS process. | pid |
+| opensips_pkmem_real_used_size | Amount of private memory requested by the OpenSIPS process, including allocator-specific metadata. | pid |
+| opensips_pkmem_total_size | Total size of private memory available to the OpenSIPS process. | pid |
+| opensips_pkmem_used_size | Amount of private memory requested and used by the OpenSIPS process. | pid |
+| opensips_registrar_default_expire | Value of default_expire parameter. | |
+| opensips_registrar_max_contacts | Value of max_contacts parameter. | |
+| opensips_registrar_max_expires | Value of max_expires parameter. | |
+| opensips_registrar_registrations | Number of registrations. | type |
+| opensips_shmem_fragments | Total number of fragments in the shared memory. | |
+| opensips_shmem_free_size | Free memory available. Computed as total_size - real_used_size | |
+| opensips_shmem_max_used_size | Maximum amount of shared memory ever used by OpenSIPS processes. | |
+| opensips_shmem_real_used_size | Amount of shared memory requested by OpenSIPS processes + malloc overhead | |
+| opensips_shmem_total_size | Total size of shared memory available to OpenSIPS processes. | |
+| opensips_shmem_used_size | Amount of shared memory requested and used by OpenSIPS processes. | |
+| opensips_sl_received_ACKs | The number of received_ACKs. | |
+| opensips_sl_replies | The number of replies. | type |
+| opensips_sl_sent_err_replies_total | The total number of sent_err_replies. | |
+| opensips_sl_sent_replies_total | The total number of sent_replies. | |
+| opensips_tm_inuse_transactions | Number of transactions existing in memory at current time. | |
+| opensips_tm_local_replies_total | Total number of replies local generated by TM module. | |
+| opensips_tm_received_replies_total | Total number of total replies received by TM module. | |
+| opensips_tm_relayed_replies_total | Total number of replies received and relayed by TM module. | |
+| opensips_tm_transactions_total | Total number of transactions. | type |
+| opensips_uri_negative_checks | Amount of negative URI checks. | |
+| opensips_uri_positive_checks | Amount of positive URI checks. | |
+| opensips_userloc_registered_users_total | Total number of AOR existing in the USRLOC memory cache for all domains. | |
+| opensips_usrloc_contacts | Number of contacts existing in the USRLOC memory cache for that domain. | domain |
+| opensips_usrloc_expires | Total number of expired contacts for that domain. | domain |
+| opensips_usrloc_users | Number of AOR existing in the USRLOC memory cache for that domain. | domain |
+
+## Processors
+
+There are processors available per 'module' of OpenSIPS. The processors take the
+statistics from the OpenSIPS socket and turn it into a Prometheus metric. You can 
+recognise a processor by the naming convention of the metrics. 
+For example the`opensips_core_replies` metric comes from the core module and its 
+processor can be found in `./processors/core_processor`.
+
+You can find out more about the available modules in the OpenSIPS documentation.
+At this time not all modules have a processor written for them. (help wanted!)
+
+### Filtering enabled processors
+It is possible to select what processors you want metrics from. You can do this by
+appending `collect[]` parameters to your request. If for example you only want to
+get metrics about the [core](http://www.opensips.org/Documentation/Interface-CoreStatistics-1-11) 
+and [usrloc](http://www.opensips.org/html/docs/modules/1.11.x/usrloc.html#idp5699792) 
+module you can do this as follows:
+```
+curl localhost:9737/metrics?collect[]=core:&collect[]=usrloc:
+```
+
+**_Note: You have to append `:` to the module name for this to work._**
 ## Development
 
 To work on opensips_exporter, get a recent [Go], get a recent [dep], and
@@ -19,5 +107,10 @@ implementation of the interactions with OpenSIPS needed to get statistics from
 the mi_datagram Unix socket of a running OpenSIPS. For tests, there is a mock
 in the `./internal/mock` package.
 
+Metrics from different OpenSIPS modules are extracted by processors defined in
+the `./processors` package. To extend this exporter with metrics from other modules
+create your own processor and implement the `Collector` interface. See the other
+processors for inspiration. 
+
 [Go]: https://golang.org/doc/install (Getting Started - The Go Programming Language)
 [dep]: https://golang.github.io/dep/docs/installation.html (Installation · dep)
diff --git a/opensips_exporter.go b/opensips_exporter.go
index 553b8a2..5a98fde 100644
--- a/opensips_exporter.go
+++ b/opensips_exporter.go
@@ -5,6 +5,10 @@ import (
 	"log"
 	"net/http"
 
+	"flag"
+	"os"
+	"strings"
+
 	"github.com/VoIPGRID/opensips_exporter/opensips"
 	"github.com/VoIPGRID/opensips_exporter/processors"
 	"github.com/prometheus/client_golang/prometheus"
@@ -14,6 +18,8 @@ import (
 var o *opensips.OpenSIPS
 var collectAll = []string{"core:", "shmem:", "net:", "uri:", "tm:", "sl:", "usrloc:", "dialog:", "registrar:", "pkmem:", "load:"}
 
+const envPrefix = "OPENSIPS_EXPORTER"
+
 func handler(w http.ResponseWriter, r *http.Request) {
 	collect := r.URL.Query()["collect[]"]
 	collectors := make(map[prometheus.Collector]bool)
@@ -58,28 +64,45 @@ func handler(w http.ResponseWriter, r *http.Request) {
 	h.ServeHTTP(w, r)
 }
 
+// strflag is like flag.String, with value overridden by an environment
+// variable (when present). e.g. with socket path, the env var used as default
+// is OPENSIPS_EXPORTER_SOCKET_PATH, if present in env.
+func strflag(name string, value string, usage string) *string {
+	if v, ok := os.LookupEnv(envPrefix + strings.ToUpper(name)); ok {
+		return flag.String(name, v, usage)
+	}
+	return flag.String(name, value, usage)
+}
+
+var (
+	socketPath  *string
+	metricsPath *string
+	port        *string
+)
+
 func main() {
-	listenAddress := ":9737"                 // TODO: make this a flag
-	metricsPath := "/metrics"                // TODO: maybe make this a flag
-	socketPath := "/var/run/ser-fg/ser.sock" // TODO: make this a flag or even a mandatory argument
+	port = strflag("port", "9737", "Port on which the OpenSIPS exporter listens.")
+	metricsPath = strflag("path", "/metrics", "The path where metrics will be served")
+	socketPath = strflag("socket", "/var/run/ser-fg/ser.sock", "Path to the socket file for OpenSIPS.")
+	flag.Parse()
 
 	// This part is to mock up setting up and using the Management
 	// Interface. Replace/remove this eventually.
 	var err error
-	o, err = opensips.New(socketPath)
+	o, err = opensips.New(*socketPath)
 	if err != nil {
 		log.Fatalf("failed to open socket: %v\n", err)
 	}
 
-	http.HandleFunc(metricsPath, handler)
+	http.HandleFunc(*metricsPath, handler)
 	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
 		w.Write([]byte(`<html>
 			<head><title>OpenSIPS Exporter</title></head>
 			<body>
 			<h1>OpenSIPS Exporter</h1>
-			<p><a href="` + metricsPath + `">Metrics</a></p>
+			<p><a href="` + *metricsPath + `">Metrics</a></p>
 			</body>
 			</html>`))
 	})
-	http.ListenAndServe(listenAddress, nil)
+	http.ListenAndServe(":"+*port, nil)
 }
diff --git a/processors/registrar_processor.go b/processors/registrar_processor.go
index df8349d..bf043e3 100644
--- a/processors/registrar_processor.go
+++ b/processors/registrar_processor.go
@@ -11,9 +11,9 @@ type RegistrarProcessor struct {
 
 var registrarLabelNames = []string{}
 var registrarMetrics = map[string]metric{
-	"max_expires":    newMetric("registrar", "max_expires", " Value of max_expires parameter.", registrarLabelNames, prometheus.GaugeValue),
-	"max_contacts":   newMetric("registrar", "max_contacts", " Value of max_contacts parameter.", registrarLabelNames, prometheus.GaugeValue),
-	"default_expire": newMetric("registrar", "default_expire", " Value of default_expire parameter.", registrarLabelNames, prometheus.GaugeValue),
+	"max_expires":    newMetric("registrar", "max_expires", "Value of max_expires parameter.", registrarLabelNames, prometheus.GaugeValue),
+	"max_contacts":   newMetric("registrar", "max_contacts", "Value of max_contacts parameter.", registrarLabelNames, prometheus.GaugeValue),
+	"default_expire": newMetric("registrar", "default_expire", "Value of default_expire parameter.", registrarLabelNames, prometheus.GaugeValue),
 	"accepted_regs":  newMetric("registrar", "registrations", "Number of registrations.", []string{"type"}, prometheus.CounterValue),
 	"rejected_regs":  newMetric("registrar", "registrations", "Number of registrations.", []string{"type"}, prometheus.CounterValue),
 }