Made companding law for SS7 calls only determined by SS7 signaling type.

For SS7, the companding law for a call was chosen inconsistently depending
upon ss7type (ITU vs ANSI) and the DAHDI companding default (T1 vs E1).
For incoming calls, the companding law was determined by ss7type.  For
outgoing calls, the companding law was determined by the DAHDI default.
With the wrong combination you would get A-law/u-law conflicts.  An
A-law/u-law conflict sounds like bad static on the line.

SS7 ITU  signaling with E1 line: ok
SS7 ITU  signaling with T1 line: noise
SS7 ANSI signaling with E1 line: noise
SS7 ANSI signaling with T1 line: ok

* Fix the companding law used to be determined by the SS7 signaling type
only.
........

Merged revisions 373090 from http://svn.asterisk.org/svn/asterisk/branches/1.8
........

Merged revisions 373101 from http://svn.asterisk.org/svn/asterisk/branches/10


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/11@373107 65c4cc65-6c06-0410-ace0-fbb531ad65f3

channels/sig_ss7.c

@@ -570,6 +570,7 @@ static void ss7_start_call(struct sig_ss7_chan *p, struct sig_ss7_linkset *links
 		p->call_level = SIG_SS7_CALL_LEVEL_SETUP;
 	}
 
+	/* Companding law is determined by SS7 signaling type. */
 	if (linkset->type == SS7_ITU) {
 		law = SIG_SS7_ALAW;
 	} else {
@@ -1872,6 +1873,13 @@ struct ast_channel *sig_ss7_request(struct sig_ss7_chan *p, enum sig_ss7_law law
 {
 	struct ast_channel *ast;
 
+	/* Companding law is determined by SS7 signaling type. */
+	if (p->ss7->type == SS7_ITU) {
+		law = SIG_SS7_ALAW;
+	} else {
+		law = SIG_SS7_ULAW;
+	}
+
 	sig_ss7_set_outgoing(p, 1);
 	ast = sig_ss7_new_ast_channel(p, AST_STATE_RESERVED, law, transfercapability, p->exten, requestor);
 	if (!ast) {