Telephone interface questions

[Skarr11]

Greetings!

I'm working on a personal project that involves interfacing a PIC micro to the telephone and dialing out a specific phone number using DTMF tones generated by the PIC. I am using a 16F876A and am following a schematic I found in the old Basic Stamp Nuts & Volts articles (NV 19 Fig 19-1, see attachment). I have recreated the circuit verbatim with the following exception:

-I am using .1uF capacitors and 100 ohm resistors on the tip and ring lines in place of relays/switches

I have constructed the circuit and written a really simple PBP program just to see if I can connect, shown below.

Given all of this, the circuit doesn't work. The code sends the tones to the speaker and to the LCD, so I know that's working, so it's something in the circuit. I have read on this forum that for phone circuits the oscillator should be 20 MHz, but I will admit I haven't tried that yet. I'll do that later today/tomorrow. Just wanted to get this out there in case anyone saw something glaringly wrong with the circuit.

I'd appreciate any advice anyone can provide, troubleshooting the circuit, etc.

' PIC16F876 to predefined connections:
'
' PIC 		    LCD		Other Connections
' ------		-------		-----------------------------          
' OSC1			Resonator - 4 mhz
' OSC2			Resonator - 4 Mhz
' MCLR			Vdd via 1k resistor
' Vdd			5v
' Vss			Gnd
' RB2           Output to serial LCD
' RB4           Output to speaker
' RB5           Output to phone line

' -----[ Revision History ]------------------------------------------------
'
' ----[ Includes / Defines ]-------------------------------------------
'
INCLUDE "MODEDEFS.BAS"  'This statement is needed for serout defines.

Define LOADER_USED 1     'Only required if bootloader used to program PIC
'define osc 20               'Oscillator speed is 20 MHz

' -----[ Constants ]-------------------------------------------------------
 
' -----[ Variables ]-------------------------------------------------------
'
' -----[ Initialization ]--------------------------------------------------
'
' -----[ Main Code ]-------------------------------------------------------
'

Start:
    serout 2,N2400,[254,1]
    serout 2,N2400,["DIALING...",254,192]
    pause 1000
    DTMFout 4,[1,8,1,8]
    DTMFout 5,[1,8,1,8]
    serout 2,N2400,[#1,32,#8,32,#1,32,#8]
    pause 1000
    Goto Start              ' Loop back and do it all again