DTMF tone issue have improved dramatically over the years and rarely seen as a problem except under certain conditions:
1) If related to inbound calls to your Strategic Voice Solutions IVR/Auto Attendant, this may be tied to a Cellular Phone which are know to have jitter and delay problems due to the connection ro cell tower handoffs. they sometimes break up the DTMF tone and sometimes duplicate a single digit tone into two. In this event, either pressing the digit the second time works or the spit of the DTMF tone can cause it to jump to the next selection in an ivr and with the second DTMF tone selection which you did not request. If not a cell phone, a SIP originated call into the Strategic Voice Solutions IVR maybe from a platform utlizing poor choices like G.729 codecs with SIP INFO DTMF transport methods or simply very low cost grey routes with poor quality.
2) For outbound calls to services or companies with IVR's, this can be tied to several possible issues:
The Phone or SIP device is not set for RFC2833 DTMF Transport Method - There are three choices for DTMF transport, though most phones and SIP devices default to RFC2833 today. There is inband DTMF, SIP INFO and RFC2833. Both Inband and SIP INFO are very unreliable. Ensure that the phone is set for strict and only RFC2833
The phone or SIP Device is not set for G711u CODEC priority - In some cases the CODEC priorty may be changed or altered for some reason and not be set to G711u as the priorty codec. In this event, it is possible to create a Asymmetric CODEC issue where G711u is one direction and G.729 is in the other direction which can cause one way audio and DTMF issues. Ensure that G711u is at the top of the priority and eliminate any other CODECS if possible.
The Phone or SIP Device Audio or DTMF level is set to low - In some rare cases the default setting is not transmitting the DTMF tones at a high enough level or it may have been changed for some reason to a lower level. This is especially true when communicating to Older Phone Systems and systems interfacing with older PSTN analog connections. Try to find a DTMF level adjustment or if there is none, increase the overall Audio output level.
The Phone or Device Caller ID is not set for a number (Anonymous)- If you do not assign a Caller ID (Map CLID) to the phone or device, it will default to "Anonymous" which means the outbound carrier will not see a Caller ID and possibly be penalized (charged a hire rate) to terminate the call. In some cases they will route the call to a low quality route that will not charge them for lack of a Caller ID (required to do proper billing on their end). This route may suffer from Audio and DTMF issues.
Outbound Carrier Issues - In some cases the Strategic Voice Solutions outbound carrier may have a problem in their system or downstream. This is not as likely, but can be proven with rerouting to an alternate carrier. This requires Technical Support to be involved.