The term “pseudo-variable” is used for special tokens that can be given as parameters to different script functions and they will be replaced with a value before the execution of the function.

The beginning of a “pseudo-variable” is marked by the character “$”. If you want to have the character “$” just double it “$$”.

There is a set of predefined pseudo-variables, which have the name composed from one or more characters, and special pseudo-variables that are references to dynamic fields (AVP and Headers).

Pseudo-Variables are implemented by various modules, most of them are provided by pv.

Pseudo-variables can be used with many modules, among them:

• acc
• avpops
• htable
• textops
• uac
• xlog

Predefined pseudo-variables are listed in alphabetical order.

$$ - represents the character '$'

$ai - reference to URI in request's P-Asserted-Identity header (see RFC 3325)

$adu - URI from Authorization or Proxy-Authorization header. This URI is used when calculating the HTTP Digest Response.

$ar - realm from Authorization or Proxy-Authorization header

$au - user part of username from Authorization or Proxy-Authorization header

$ad - domain part of username from Authorization or Proxy-Authorization header

$aU - whole username from Authorization or Proxy-Authorization header

$Au - username for accounting purposes. It's a selective pseudo variable (inherited from acc module). It returns $au if exits or From username otherwise.

$branch(name) - reference to attribute 'name' of a branch

This pseudo variable gives you access to the “additional branches” only, not to the “main branch”. E.g. if there are 3 clients registered for the same AoR, after lookup() you will have one contact in the “main branch” and two “additional branches”. Using $branch() you can access the additional branches, the main branch can be accessed using $ru and $du. (Note: In branch_routes there is no distinction between the main and the additional branches - the branch_route will be called for all of them.)

The 'name' can be:

• uri - return uri of the branch
• dst_uri - return destination uri (next hop address)
• q - return the q value of the branch
• path - return the path vector for the branch
• send_socket - return the socket to be used to send the branch
• flags - return the branch flags value
• count - return the number of the branches

The PV can take an index to access a specif branch: $(branch(name)[index])

Example:

$var(i)=0;
while($var(i)<$branch(count))
{
   xlog("$(branch(uri)[$var(i)])\n");
   $var(i) = $var(i) + 1;
}

Starting with 3.1.0, you can assign value per attribute. Index can be used to update a specific branch:

$(branch(attr)[index]) = value;

If index is missing, first branch is used. If index is -1 the last branch is used.

Assigning $null to uri attribute will drop the branch, for the rest of attributes will just set the value to null.

$(branch(uri)[2]) = "sip:test@kamailio.org;transport=sctp";

$br - reference to request's first branch

It is R/W variable, you can assign values to it directly in configuration file (will add a new branch).

$bR - reference to request's all branches

$bf - reference to branch flags of branch 0 (RURI) - decimal output

$bF - reference to branch flags of branch 0 (RURI) - hexa output

$bs - body size

$ci - reference to body of call-id header

$cl - reference to body of content-length header

$cs - reference to the sequence number in the cseq header. The method in the CSeq header is identical to the request method, thus use $rm to get the methode (works also for responses).

$ct - reference to body of contact header

$cT - reference to body of content-type header

$dd - reference to domain of destination uri (without port)

$di - reference to Diversion header URI

$dip - reference to Diversion header “privacy” parameter value

$dir - reference to Diversion header “reason” parameter value

$dic - reference to Diversion header “counter” parameter value

$dp - reference to port of destination uri

$dP - reference to transport protocol of destination uri

$ds - reference to destination set

$du - reference to destination uri

If loose_route() returns TRUE a destination uri is set according to the first Route header. $du is also set if lookup() function of 'registrar' module finds contact(s) behind NAT.

It is R/W variable (you can assign values to it directly in configuration file)

To reset $du:

$du = null;

$err.class - the class of error (now is '1' for parsing errors)

$err.level - severity level for the error

$err.info - text describing the error

$err.rcode - recommended reply code

$err.rreason - recommended reply reason phrase

$fd - reference to domain in URI of 'From' header

$fn - reference to display name of 'From' header

$ft - reference to tag parameter of 'From' header

$fu - reference to URI of 'From' header

$fU - reference to username in URI of 'From' header

$mb - reference to SIP message buffer

$mf - reference to message/transaction flags set for current SIP request

It is R/W variable (you can assign values to it directly in configuration file)

$mF -reference to message/transaction flags set for current SIP request in hexa-decimal

It is R/W variable (you can assign values to it directly in configuration file)

$mi - reference to SIP message id

$ml - reference to SIP message length

$mt - returns 1 if the sip message is a request, returns 2 if the sip message is a reply

$od - reference to domain in request's original R-URI

$op - reference to port of original R-URI

$oP - reference to transport protocol of original R-URI

$ou - reference to request's original URI

$oU - reference to username in request's original URI

$pd - reference to domain in request's P-Preferred-Identity header URI (see RFC 3325)

$pn - reference to Display Name in request's P-Preferred-Identity header (see RFC 3325)

$pp - reference to process id (pid)

$pr or $proto - protocol of received message (UDP, TCP, TLS, SCTP)

$pU - reference to user in request's P-Preferred-Identity header URI (see RFC 3325)

$pu - reference to URI in request's P-Preferred-Identity header (see RFC 3325)

$rd - reference to domain in request's URI (without port) or to the Namespace Specific String of a URN (see RFC 2141)

It is R/W variable (you can assign values to it directly in configuration file)

$rb - reference to message body

$rc - reference to returned code by last invoked function

$retcode - same as $rc

$re - reference to Remote-Party-ID header URI

$rm - reference to request's method. Works also for replies (by using the CSeq header)

$rmid - returns internal integer representation of SIP method type

$rp - reference to port of R-URI

It is R/W variable (you can assign values to it directly in configuration file)

$rP - reference to transport protocol of R-URI

$rr - reference to reply's reason

$rs - reference to reply's status

$rt - reference to URI of refer-to header

$ru - reference to request's URI

It is R/W variable (you can assign values to it directly in configuration file)

$rU - reference to username in request's URI or to the Namespace Identifier of a URN (see RFC 2141)

It is R/W variable (you can assign values to it directly in configuration file)

$rz - returns R-URI scheme, possible values: sip, sips, tel, tels and urn, R-URI scheme parsing error should be reflected by value: none

$Ri - reference to IP address of the interface where the request has been received

$Rp - reference to the port where the message was received

$sf - reference to script flags - decimal output

$sF - reference to script flags - hexa output

$si - reference to IP source address of the message

$sp - reference to the source port of the message

$stat(name) - return the value of statistic item specified by 'name'

$fs - reference to the forced socket for message sending (if any) in the form proto:ip:port

It is R/W variable (you can assign values to it directly in configuration file)

$td - reference to domain in URI of 'To' header

$tn - reference to display name of 'To' header

$tt - reference to tag parameter of 'To' header

$tu - reference to URI of 'To' header

$tU - reference to username in URI of 'To' header

$Tb - reference to unix timestamp of the time at which kamailio was started

$Tf - reference string formatted time

Note: the system time is retrieved only once for each processed SIP message. Subsequent calls of $Tf for same SIP message will return same value.

$TF - reference string formatted time

Note: the system time is computed for each call of $TF. Subsequent calls of $TF for same SIP message may return different values.

$Ts - reference to unix time stamp

Note: the system time is retrieved only once for each processed SIP message. Subsequent calls of $Ts for same SIP message will return same value.

$TS - reference to unix time stamp

Note: the system time is computed for each call of $TS. Subsequent calls of $TS for same SIP message may return different values.

$ua - reference to user agent header field

$avp(id) - the value of the AVP identified by 'id'.

$(avp(id)[N]) - represents the value of N-th AVP identified by 'id'.

The 'id' can be:

• “[(s|i):]name” - name is the id of an AVP; 's' and 'i' specifies if the id is string or integer. If missing, it is considered to be string.
• “name” - the name is an AVP alias, or if the alias is not found, it is a string name
• pseudo variable - if value of pv is integer, id is integer, if string, id is string

$(avp(id)[0]) can be written in shorter form as $avp(id) and $avp(s:name) as $avp(name).

AVPs are special variables that are attached to SIP transactions. It is a list of pairs (name,value). Before the transaction is created, the AVP list is attached to SIP request. Note that the AVP list works like a stack, last added value is retrieved first, and there can be many values for same AVP name, an assignment to the same AVP name does not overwrite old value, it will add the new value in the list.

To delete the first AVP with name 'id' you have to assign to it '$null':

$avp(id) = $null;

To delete all the AVP with name 'id' you have to assign $null to the index '*':

$(avp(id)[*]) = $null;

To overwrite the value of the AVP with name 'id' you have to assign the new value to the index '*':

$(avp(id)[*]) = newvalue;

The value of an AVP can be integer or string. To assign a value as string, it has to be enclosed in double quotes. To assign the value as integer, it has to be a valid number given without quotes.

Example of usage:

$avp(x) = 1;  # assign of integer value
$avp(x) = 2;
$avp(y) = "abc"; # assign of string value
if($(avp(x)[1])==1) {
  ...
}
$(avp(x)[1]) = $null;

It is R/W variable (you can assign values to it directly in configuration file).

$hdr(name) - represents the body of first header identified by 'name'

$(hdr(name)[N]) - represents the body of the N-th header identified by 'name'.

If [N] is omitted then the body of the first header is printed. The first header is got when N=0, for the second N=1, a.s.o. In case of a comma-separated multi-body headers, it returns all the bodies, comma-separated. To print the last header of that type, use -1, or other negative values to count from the end. No white spaces are allowed inside the specifier (before }, before or after {, [, ] symbols). When N='*', all headers of that type are printed.

The module should identify compact header names. It is recommended to use dedicated specifiers for headers (e.g., $ua for user agent header), if they are available – they are faster.

Example of usage:

if($hdr(From)=~"sip-router\.org") {
...
}

It is read-only variable. You can remove or add headers using functions from textops module.

$var(name) - refers to variables that can be used in configuration script, having integer or string value. This kind of variables are faster the AVPs, being referenced directly to memory location. The value of script variables persists over the processing of SIP messages, being specific per each SIP-Router process.

Example of usage:

$var(a) = 2; -- sets the value of variable 'a' to integer '2'
$var(a) = "2"; -- sets the value of variable 'a' to string '2'
$var(a) = 3 + (7&(~2));
$var(a) = "sip:" + $au + "@" + $fd; -- compose a value from authentication username and From URI domain

if( [ $var(a) & 4 ] ) {
  xlog("var a has third bit set\n");
}

Setting a variable to null is actually initializing the value to integer '0'. Script variables don't have NULL value.

Note: A script variable persists over the SIP-Router process in which it was initialized, so be sure of giving it a new value before reading it or you'll get the value asigned in any other previous message processed by the same SIP-Router process (pid).

It is R/W variable (you can assign values to it directly in configuration file)

pv module can be used to initialize the script variables.

$shv(name) - it is a class of pseudo-variables stored in shared memory. The value of $shv(name) is visible across all openser processes. Each “shv” has single value and it is initialised to integer 0. You can use “shvset” parameter of pv module to initialize the shared variable. The module exports a set of MI functions to get/set the value of shared variables.

Example - shv(name) pseudo-variable usage:

...
modparam("pv", "shvset", "debug=i:1")
...
if ($shv(debug) == 1) {
	xlog("request: $rm from $fu to $ru\n");
}
...

It is R/W variable (you can assign values to it directly in configuration file)

$time(name) - the PV provides access to broken-down time attributes.

The 'name' can be:

• sec - return seconds (int 0-59)
• min - return minutes (int 0-59)
• hour - return hours (int 0-23)
• mday - return the day of month (int 0-59)
• mon - return the month (int 1-12)
• year - return the year (int, e.g., 2008)
• wday - return the day of week (int, 1=Sunday - 7=Saturday)
• yday - return the day of year (int, 1-366)
• isdst - return daylight saving time status (int, 0 - DST off, >0 DST on)

Example - time(name) pseudo-variable usage:

...
if ($time(year) == 2008) {
    xlog("request: $rm from $fu to $ru in year 2008\n");
}
...

$timef(format) - return current time as formatted by strftime 'format'. See 'man strftime' to see the available time attribute specifiers.

Example:

xlog("Today is $timef(%m/%d/%y)\n");

$sel(name) - return the value of select specified by name. select refers a class of config variables introduced by SER 2.0, allowing to select and return parts of sip messages and not only.

List of available selects:

• http://sip-router.org/wiki/cookbooks/selects/devel

Example:

if($sel(via[1].host)=="10.10.10.10")
{
  ...
}

$snd(name) - return attributes of the address from where the request is going to be sent (local socket).

$sndfrom(name) - return attributes of the address from where the request is going to be sent (local socket, same as $snd(name)).

$sndto(name) - return attributes of the address to where the request is going to be sent (remote socket).

They are available in onsend_route. The name can be:

• ip - IP address of destination
• af - address family to be used to send (numeric)
• port - port of destination address
• proto - transport protocol to be used to send (numeric)
• buf - entire send buffer as string
• len - length of outgoing packet (length of above buf)

Example:

onsend_route {
  if($snd(ip)=="10.10.10.10")
  {
    ...
  }
}

$BM_time_diff - the time difference elapsed between calls of bm_start_timer(name) and bm_log_timer(name). The value is 0 if no bm_log_timer() was called.

Return the attribute of the current processed dialog.

It is R/O variable.

The 'attr' can be:

• h_id - hash id
• h_entry - hash entry
• ref - reference count
• state - state of dialog
• to_rs - To route set
• from_rs - From route set
• dflags - dialog internal flags
• sflags - dialog script flags
• callid - sip call id
• to_uri - To uri
• to_tag - To tag
• from_uri - From uri
• from_tag - From tag
• toroute - timeout route
• lifetime - timeout inteval
• start_ts - start timestamp
• to_cseq - To CSeq
• from_cseq - From CSeq
• to_contact - To contact address
• from_contact - From contact address
• to_bindaddr - To bind address
• from_bindaddr - From bind address

Return the attribute of the context for current processed dialog.

It is R/W variable.

The 'attr' can be:

• set
• flags
• timeout_route
• timeout_bye

Store and retrieve custom variable for current processed dialog.

It is R/W variable.

The 'key' can be any string.

Access hash table entries.

It is R/W variable, you can assign values to it directly in configuration file.

The “htname” must be a hash table name defined via “htable” parameter.

The “key” can be:

• static string - set of characters without pseudo-variables
• dynamic string - set of characters that include pseudo-variables. The pseudo-variables will be evaluated at runtime.

...
modparam("htable", "htable", "a=>size=4;")
...
$sht(a=>$au) = 1;
$sht(a=>$ru) = $fu;
...

Access hash table entry expire value. Value represents the seconds until the htable entry will expire and be deleted from htable.

It is R/W variable, you can assign values to it directly in configuration file.

The “htname” must be a hash table name defined via “htable” parameter and have auto-expire greater than 0.

The “key” can be:

• static string - set of characters without pseudo-variables
• dynamic string - set of characters that include pseudo-variables. The pseudo-variables will be evaluated at runtime.

...
modparam("htable", "htable", "a=>size=4;autoexpire=120;")
...
$sht(a=>$au) = 1;
$shtex(a=>$au) = 10;
...

Count items matching the name by regexp.

The “htname” must be a hash table name defined via “htable” parameter.

The exp can be:

• reqexp - match by regular expression 'regexp'
• ~~regexp - match by regular expression 'regexp'
• ~%prefix - match by right prefix
• %~prefix - match by left prefix
• ==value - match by string value
• eqvalue - match by integer value
• * * - (two asterisks next to each other) - count all items

The exp can contain pseudo-variables.

...
modparam("htable", "htable", "a=>size=4;")
...
$sht(a=>abc) = 1;
$shtex(a=>ade) = 10;
xlog("$shtcn(a=>a.*)");
...

Count items matching the value by regexp.

The “htname” must be a hash table name defined via “htable” parameter.

The exp must follow same rules as for $shtcn(…).

...
modparam("htable", "htable", "a=>size=4;")
...
$sht(a=>abc) = "xyz";
$shtex(a=>ade) = "xwt";
xlog("$shtcv(a=>x.*)");
...

Atomic increment of the value for the hash table item.

...
modparam("htable", "htable", "a=>size=4;")
...
$sht(a=>$au) = 1;
xlog("==== $shtinc(a=>$au)\n");
...

Atomic decrement of the value for the hash table item.

...
modparam("htable", "htable", "a=>size=4;")
...
$sht(a=>$au) = 1;
xlog("==== $shtdec(a=>$au)\n");
...

Access hash table entries stored in the memcached server.

It is R/W variable, you can assign values to it directly in configuration file.

The “key” can be:

• static string - set of characters without pseudo-variables
• dynamic string - set of characters that include pseudo-variables. The pseudo-variables will be evaluated at runtime.

...
$mct($au) = 1;
$mct($ru) = $fu;
$mct(test) = 1;
xlog("stored value is $mct(test)");
$mct(test) = null; # delete it
xlog("stored value is $mct(test)"); # will return <null>
...

Do a atomic increment operation on the value stored in memcached. You need to add a value previously.

It is R/W variable, you can assign values to it directly in configuration file.

The “key” can be:

• static string - set of characters without pseudo-variables
• dynamic string - set of characters that include pseudo-variables. The pseudo-variables will be evaluated at runtime.

...
$mct(cnt) = 1;
$mcinc(cnt) = 2; # increment by 2
xlog("counter is now $mct(cnt)");
...

Do a atomic decrement operation on the value stored in memcached. You need to add a value previously.

It is R/W variable, you can assign values to it directly in configuration file.

The “key” can be:

• static string - set of characters without pseudo-variables
• dynamic string - set of characters that include pseudo-variables. The pseudo-variables will be evaluated at runtime.

...
$mct(cnt) = 10;
$mcdec(cnt) = 2; # decrement by 2
xlog("counter is now $mct(cnt)");
...

• name - id to refer the documet
• spec - specifier:
  • doc - set/get the document as text
  • xpath:xpath-expression - evaluate xpath expression

Example:

$xml(x=>doc) = '<?xml version="1.0" encoding="UTF-8"?><a><b>test</b></a>';
xlog("content of node b: $xml(x=>xpath:/a/b/text())\n");
$xml(x=>xpath:/a/b) = "1234";

• the index (starting with 1 for the first branch) of the branch for which is executed the branch_route[]. If used outside of branch_route[] block, the value is '0'.

• the code of the reply, as follows: in request_route will be the last stateful sent reply; in reply_route will be the current processed reply; in failure_route will be the negative winning reply. In case of no-reply or error, '0' value is returned

• can be used in reply routes or inside the modules to get access to attributes of the request belonging to same transaction as the reply

route {
  t_on_reply("1");
  t_relay();
}

onreply_route[1] {
  xlog("Request SRCIP:PORT = $T_req($si):$T_req($sp)\n");
}

• can be used in failure routes or inside the modules to get access to attributes of the winning reply belonging to same transaction as the request

route {
  t_on_failure("1");
  t_relay();
}

failure_route[1] {
  xlog("Reply SRCIP:PORT = $T_rpl($si):$T_rpl($sp)\n");
}

• can be used in request routes or inside the modules to get access to attributes of the INVITE request while processing a CANCEL.

route {
  if(is_method("CANCEL"))
  {
     if($T_inv($mf) & 1 )
     {
        # first flag is set in the INVITE transaction
     }
  }
}

• pseudo-variable class to access TM attributes

The name can be:

• id_index - return the internal index of current transaction
• id_label - return the internal label of current transaction
• reply_code - alias to $T_reply_code
• branch_index - alias to $T_branch_idx
• reply_type - 1 if it is a local generated reply, 0 - if no reply for transaction or it is a received reply

Note: the pair (id_index,id_label) uniquely identifies a transaction.

• used to build the input for uac_send_req() function of UAC module

key can be:

• method - SIP method
• ruri - request URI
• furi - From URI
• turi - To URI
• ouri - Outbound proxy URI
• hdrs - SIP Headers
• body - Body
• all - alias useful to rest all fields - $uac_req(all) = null;

$uac_req(method)="OPTIONS";
$uac_req(ruri)="sip:kamailio.org";
$uac_req(furi)="sip:kamailio.org";
$uac_req(turi)="sip:kamailio.org";
uac_send_req();

• Number of Record Routes in received SIP request or reply.

• If topmost Record Route in received SIP request or reply is a double Record Route, value of $rr_top_count is 2. If it a single Record Route, value of $rr_top_count is 1. If there is no Record Route(s), value of $rr_top_count is 0.

• return the key of fetched item from queue q

• return the value of fetched item from queue q

...
mq_add("myq", "$rU", "call from $fU at $Tf");
...
while(mq_fetch("myq"))
{
   xlog("$mqk(myq) - $mqv(myq)\n");
}
...

Seconds and microseconds taken from struct timeval.

• $TV(s) - seconds (cached at first call per sip message)
• $TV(u) - microseconds (cached at first call per sip message)
• $TV(sn) - seconds (not cached)
• $TV(un) - microseconds (not cached)
• $TV(Sn) - string representation seconds.microseconds (not cached)

Return attributes of next hop for the SIP request. Address is taken from dst_uri, if set, if not from new r-uri or original r-uri.

• $nh(u) - uri (lower case u)
• $nh(U) - username (upper case u)
• $nh(d) - domain
• $nh(p) - port (lower case p)
• $nh(P) - transport protocol (upper case p)

Variables exported by GeoIP module, returning geo-location attributes. The attributes are populated upon calling function geoip_match(ipaddr, pvc).

pvc (container id) is second parameter of geoip_match(..) and key can be:

• cc - country code
• tz - time zone
• zip - postal code
• lat - latitude
• lon - longitude
• dma - dma code
• ips - ip start
• ipe - ip end
• city - city
• area - area code
• regc - region
• regn - region name
• metro - metro code

You can call several time geoip_match(ipaddr, pvc) with different ip address and containers in your config, to compare, for example, attributes of source and destination of a call.

geoip_match("$si", "src");
geoip_match("$nh(d)", "dst");
 
if($gip(src=>cc)==$gip(dst=>cc))
{
    # source and destination from same country
}

• URL of http request.

This class of pseudo-variables is exported by MSRP module and give access to attributes of MSRP frames.

The entire content of MSRP frame - first line, headers, body and end-line.

The body of MSRP frame.

The code of MSRP replies.

The headers in a MSRP frame.

The body of Message-Id header.

The method of a MSRP request.

The length of entire MSRP frame.

The session id for MSRP frame. It is taken from the first MSRP URI in To-Path header.

The reason text in a MSRP reply.

The URI for current hop - it is the first URI in To-Path header.

The length of the body in MSRP frame.

The transaction ID from the first line of MSRP frame.

The MSRP URI of the previous hop - the first address in From-Path header.

The URI of the next hop - the second address in To-Path header.

The last hop URI - the last address in To-Path header.

The address of the previous hop set as MSRP URI using received source IP and port.

The local socket where the MSRP frame was received, set as **proto:ipaddr:port“.

The URI of the first hop - the last address in From-Path header.

The number of previous hops - it is the number of addresses in From-Path header.

The number of next hops - it is the number of addresses in To-Path header minus 1 (the first address in To-Path is current hop).

The internal integer id for TCP/TLS connection.

These pseudo variables are exported, and mainly used, by xlog module to print messages in many colors (foreground and background) using escape sequences.

$C(xy) - reference to an escape sequence. “x” represents the foreground color and “y” represents the background color.

Colors could be:

• x : default color of the terminal
• s : Black
• r : Red
• g : Green
• y : Yellow
• b : Blue
• p : Purple
• c : Cyan
• w : White

A few examples of usage.

Example 1. Pseudo-variables usage

...
avp_aliases="uuid=I:50"
...
route {
...
    $avp(uuid)="caller_id";
    $avp(i:20)= $avp(uuid) + ": " + $fu;
    xdbg("$(C(bg))avp(i:20)$(C(xx)) [$avp(i:20)] $(C(br))cseq$(C(xx))=[$hdr(cseq)]\n");
...
}
...

Following are some examples how RURI and DURI are parsed, for SIP-URIs, tel-URIs and Service-URNs:

 === Request URI contains SIP URI ===
$ru = "sip:example.com"
$rz = "sip"
$rU = "<null>"
$rd = "example.com"
$rp = "5060"
$rP = "UDP"

=== Request URI contains SIP URI ===
$ru = "sips:john.q.public:hispw@example.com:6061;transport=tls;foo=bar"
  $rz = "sips"
  $rU = "john.q.public"
  $rd = "example.com"
  $rp = "6061"
  $rP = "tls"

=== Request URI contains service URN ===
$ru = "urn:service:sos.fire"
  $rz = "urn"
  $rU = "service"
  $rd = "sos.fire"
  $rp = "5060"
  $rP = "UDP"

=== Request URI contains tel: URI ===
$ru = "tel:+1-201-555-0123"
  $rz = "tel"
  $rU = "+1-201-555-0123"
  $rd = "<null>"
  $rp = "5060"
  $rP = "UDP"

=== Request URI contains tel: URI with phone-context ===
$ru = "tel:7042;phone-context=example.com"
  $rz = "tel"
  $rU = "7042"
  $rd = "<null>"
  $rp = "5060"
  $rP = "UDP"

=== Destination URI (must be a SIP(S) URI) ===
$du = "sip:example.com:6061;transport=tls;foo=bar"
  $dd = "example.com"
  $dp = "6061"
  $dP = "tls"