Index: drivers/dahdi/wctdm.c
===================================================================
--- drivers/dahdi/wctdm.c	(revision 6690)
+++ drivers/dahdi/wctdm.c	(working copy)
@@ -227,6 +227,8 @@
 		        int lastpol;
 		        int polarity;
 		        int polaritydebounce;
+			int readcid;
+			unsigned int cidtimer;
 		} fxo;
 		struct fxs {
 			int oldrxhook;
@@ -283,22 +285,23 @@
 static unsigned int battalarm;
 static unsigned int battthresh;
 static int ringdebounce = DEFAULT_RING_DEBOUNCE;
-static int fwringdetect = 0;
-static int debug = 0;
-static int robust = 0;
-static int timingonly = 0;
-static int lowpower = 0;
-static int boostringer = 0;
-static int fastringer = 0;
-static int _opermode = 0;
+static int fwringdetect;
+static int debug;
+static int robust;
+static int timingonly;
+static int lowpower;
+static int boostringer;
+static int fastringer;
+static int _opermode;
 static char *opermode = "FCC";
-static int fxshonormode = 0;
-static int alawoverride = 0;
-static int fastpickup = 0;
-static int fxotxgain = 0;
-static int fxorxgain = 0;
-static int fxstxgain = 0;
-static int fxsrxgain = 0;
+static int fxshonormode;
+static int alawoverride;
+static int fastpickup;
+static int fxotxgain;
+static int fxorxgain;
+static int fxstxgain;
+static int fxsrxgain;
+static int dtmf;
 
 static int wctdm_init_proslic(struct wctdm *wc, int card, int fast , int manual, int sane);
 
@@ -391,6 +394,41 @@
 	}
 }
 #endif
+
+static void wctdm_dtmfcheck_fakepolarity(struct wctdm *wc, int card, int x)
+{
+	int sample;
+	struct fxo *const fxo = &wc->mod[card].fxo;
+
+	/* only look for sound on the line if dtmf flag is on, it is an fxo
+	 * card and line is onhook */
+	if (!dtmf || !(wc->cardflag & (1 << card)) ||
+	    wc->modtype[card] != MOD_TYPE_FXO || fxo->offhook)
+		return;
+
+	/* don't look for noise if we're already processing it, or there is a
+	 * ringing tone */
+	if (!fxo->readcid && !fxo->wasringing  &&
+	    wc->intcount > fxo->cidtimer + 400) {
+		sample = DAHDI_XLAW(wc->chans[card]->readchunk[x],
+				    wc->chans[card]);
+		if (sample > 2000 || sample < -2000) {
+			fxo->readcid = 1;
+			fxo->cidtimer = wc->intcount;
+			if (debug) {
+				printk(KERN_DEBUG "DTMF CLIP on %i\n",
+				       card + 1);
+			}
+			dahdi_qevent_lock(wc->chans[card],
+					  DAHDI_EVENT_POLARITY);
+		}
+	} else if (fxo->readcid && wc->intcount > fxo->cidtimer + 2000) {
+		/* reset flags if it's been a while */
+		fxo->cidtimer = wc->intcount;
+		fxo->readcid = 0;
+	}
+}
+
 static inline void wctdm_receiveprep(struct wctdm *wc, unsigned char ints)
 {
 	volatile unsigned int *readchunk;
@@ -405,21 +443,29 @@
 #ifdef __BIG_ENDIAN
 		if (wc->cardflag & (1 << 3))
 			wc->chans[3]->readchunk[x] = (readchunk[x]) & 0xff;
+		wctdm_dtmfcheck_fakepolarity(wc, 3, x);
 		if (wc->cardflag & (1 << 2))
 			wc->chans[2]->readchunk[x] = (readchunk[x] >> 8) & 0xff;
+		wctdm_dtmfcheck_fakepolarity(wc, 2, x);
 		if (wc->cardflag & (1 << 1))
 			wc->chans[1]->readchunk[x] = (readchunk[x] >> 16) & 0xff;
+		wctdm_dtmfcheck_fakepolarity(wc, 1, x);
 		if (wc->cardflag & (1 << 0))
 			wc->chans[0]->readchunk[x] = (readchunk[x] >> 24) & 0xff;
+		wctdm_dtmfcheck_fakepolarity(wc, 0, x);
 #else
 		if (wc->cardflag & (1 << 3))
 			wc->chans[3]->readchunk[x] = (readchunk[x] >> 24) & 0xff;
+		wctdm_dtmfcheck_fakepolarity(wc, 3, x);
 		if (wc->cardflag & (1 << 2))
 			wc->chans[2]->readchunk[x] = (readchunk[x] >> 16) & 0xff;
+		wctdm_dtmfcheck_fakepolarity(wc, 2, x);
 		if (wc->cardflag & (1 << 1))
 			wc->chans[1]->readchunk[x] = (readchunk[x] >> 8) & 0xff;
+		wctdm_dtmfcheck_fakepolarity(wc, 1, x);
 		if (wc->cardflag & (1 << 0))
 			wc->chans[0]->readchunk[x] = (readchunk[x]) & 0xff;
+		wctdm_dtmfcheck_fakepolarity(wc, 0, x);
 #endif
 	}
 #ifdef AUDIO_RINGCHECK
@@ -786,6 +832,8 @@
 				    (fxo->battery == BATTERY_PRESENT)) {
 					if (!fxo->wasringing) {
 						fxo->wasringing = 1;
+						fxo->readcid = 0;
+						fxo->cidtimer = wc->intcount;
 						if (debug)
 							printk(KERN_DEBUG "RING on %d/%d!\n", wc->span.spanno, card + 1);
 						dahdi_hooksig(wc->chans[card], DAHDI_RXSIG_RING);
@@ -795,6 +843,8 @@
 				} else if (!res) {
 					if ((fxo->ringdebounce == 0) && fxo->wasringing) {
 						fxo->wasringing = 0;
+						fxo->readcid = 0;
+						fxo->cidtimer = wc->intcount;
 						if (debug)
 							printk(KERN_DEBUG "NO RING on %d/%d!\n", wc->span.spanno, card + 1);
 						dahdi_hooksig(wc->chans[card], DAHDI_RXSIG_OFFHOOK);
@@ -811,6 +861,8 @@
 				if (fxo->ringdebounce >= DAHDI_CHUNKSIZE * ringdebounce) {
 					if (!fxo->wasringing) {
 						fxo->wasringing = 1;
+						fxo->readcid = 0;
+						fxo->cidtimer = wc->intcount;
 						dahdi_hooksig(wc->chans[card], DAHDI_RXSIG_RING);
 						if (debug)
 							printk(KERN_DEBUG "RING on %d/%d!\n", wc->span.spanno, card + 1);
@@ -822,6 +874,8 @@
 				if (fxo->ringdebounce <= 0) {
 					if (fxo->wasringing) {
 						fxo->wasringing = 0;
+						fxo->readcid = 0;
+						fxo->cidtimer = wc->intcount;
 						dahdi_hooksig(wc->chans[card], DAHDI_RXSIG_OFFHOOK);
 						if (debug)
 							printk(KERN_DEBUG "NO RING on %d/%d!\n", wc->span.spanno, card + 1);
@@ -2572,6 +2626,7 @@
 module_param(fxorxgain, int, 0600);
 module_param(fxstxgain, int, 0600);
 module_param(fxsrxgain, int, 0600);
+module_param(dtmf, int, 0600);
 
 MODULE_DESCRIPTION("Wildcard TDM400P Driver");
 MODULE_AUTHOR("Mark Spencer <markster@digium.com>");
Index: drivers/dahdi/wctdm24xxp/wctdm24xxp.h
===================================================================
--- drivers/dahdi/wctdm24xxp/wctdm24xxp.h	(revision 6690)
+++ drivers/dahdi/wctdm24xxp/wctdm24xxp.h	(working copy)
@@ -190,6 +190,8 @@
 			int lastpol;
 			int polarity;
 			int polaritydebounce;
+			int readcid;
+			unsigned int cidtimer;
 			int neonmwi_state;
 			int neonmwi_last_voltage;
 			unsigned int neonmwi_debounce;
Index: drivers/dahdi/wctdm24xxp/base.c
===================================================================
--- drivers/dahdi/wctdm24xxp/base.c	(revision 6690)
+++ drivers/dahdi/wctdm24xxp/base.c	(working copy)
@@ -216,6 +216,7 @@
 static int vpmnlptype = DEFAULT_NLPTYPE;
 static int vpmnlpthresh = DEFAULT_NLPTHRESH;
 static int vpmnlpmaxsupp = DEFAULT_NLPMAXSUPP;
+static int dtmf;
 
 static int echocan_create(struct dahdi_chan *chan, struct dahdi_echocanparams *ecp,
 			   struct dahdi_echocanparam *p, struct dahdi_echocan_state **ec);
@@ -706,7 +707,7 @@
 #endif	
 }
 
-static inline void cmd_decipher_vpmadt032(struct wctdm *wc, unsigned char *readchunk)
+static void cmd_decipher_vpmadt032(struct wctdm *wc, const u8 *readchunk)
 {
 	unsigned long flags;
 	struct vpmadt032 *vpm = wc->vpmadt032;
@@ -751,7 +752,7 @@
 #endif
 }
 
-static inline void cmd_decipher(struct wctdm *wc, volatile unsigned char *readchunk, int card)
+static void cmd_decipher(struct wctdm *wc, const u8 *readchunk, int card)
 {
 	unsigned long flags;
 	unsigned char ident;
@@ -1014,8 +1015,42 @@
 #endif
 }
 
-static inline void wctdm_receiveprep(struct wctdm *wc, unsigned char *readchunk)
+static void wctdm_dtmfcheck_fakepolarity(struct wctdm *wc, int card, u8 sample8)
 {
+	u16 sample16;
+	struct fxo *const fxo = &(wc->mods[card].fxo);
+
+	/* only look for sound on the line if dtmf flag is on, it is an fxo
+	 * card and line is onhook */
+	if (!dtmf || !(wc->cardflag & (1 << card)) ||
+	    (wc->modtype[card] != MOD_TYPE_FXO) || fxo->offhook) {
+		return;
+	}
+
+	/* don't look for noise if we're already processing it, or there is a
+	 * ringing tone */
+	if (!fxo->readcid && !fxo->wasringing  &&
+	    wc->intcount > fxo->cidtimer + 400) {
+		sample16 = DAHDI_XLAW(sample8, wc->chans[card]);
+		if (sample16 > 2000 || sample16 < -2000) {
+			fxo->readcid = 1;
+			fxo->cidtimer = wc->intcount;
+			if (debug) {
+				printk(KERN_DEBUG "DTMF CLIP on %i\n",
+				       card + 1);
+			}
+			dahdi_qevent_lock(wc->chans[card],
+					  DAHDI_EVENT_POLARITY);
+		}
+	} else if (fxo->readcid && wc->intcount > fxo->cidtimer + 2000) {
+		/* reset flags if it's been a while */
+		fxo->cidtimer = wc->intcount;
+		fxo->readcid = 0;
+	}
+}
+
+static inline void wctdm_receiveprep(struct wctdm *wc, const u8 *readchunk)
+{
 	int x,y;
 	unsigned char expected;
 
@@ -1034,13 +1069,15 @@
 			if (likely(wc->initialized)) {
 				if (y < wc->type) {
 					wc->chans[y]->readchunk[x] = readchunk[y];
+					wctdm_dtmfcheck_fakepolarity(wc, y, readchunk[y]);
 				}
 			}	
 			cmd_decipher(wc, readchunk, y);
 		}
 		if (wc->vpm100) {
-			for (y=NUM_CARDS;y < NUM_CARDS + NUM_EC; y++)
+			for (y = NUM_CARDS; y < NUM_CARDS + NUM_EC; y++) {
 				cmd_decipher(wc, readchunk, y);
+			}
 		} else if (wc->vpmadt032) {
 			cmd_decipher_vpmadt032(wc, readchunk);
 		}
@@ -1359,6 +1396,8 @@
 					fxo->ringdebounce = ringdebounce / 16;
 				} else if (--fxo->ringdebounce == 0) {
 					fxo->wasringing = 0;
+					fxo->readcid = 0;
+					fxo->cidtimer = wc->intcount;
 					if (debug)
 						printk("FW NO RING on %d/%d!\n", wc->span.spanno, card + 1);
 					dahdi_hooksig(wc->chans[card], DAHDI_RXSIG_OFFHOOK);
@@ -1382,6 +1421,8 @@
 				if (fxo->ringdebounce <= 0) {
 					if (fxo->wasringing) {
 						fxo->wasringing = 0;
+						fxo->readcid = 0;
+						fxo->cidtimer = wc->intcount;
 						dahdi_hooksig(wc->chans[card], DAHDI_RXSIG_OFFHOOK);
 						if (debug)
 							printk(KERN_DEBUG "NO RING on %d/%d!\n", wc->span.spanno, card + 1);
@@ -3901,6 +3942,7 @@
 module_param(fxsrxgain, int, 0600);
 module_param(ringdebounce, int, 0600);
 module_param(fwringdetect, int, 0600);
+module_param(dtmf, int, 0600);
 module_param(latency, int, 0600);
 module_param(neonmwi_monitor, int, 0600);
 module_param(neonmwi_level, int, 0600);